test_pkey_rsa.rb: Fix test_private_encoding_encrypted in OpenSSL 4.0 FIPS

[ This is a backport to the 3.3 branch. ]

OpenSSL 4.0.0 added a check for Password-Based Key Derivation Function 2
(PBKDF2) to require the minimal password length 8 in FIPS by the following
commit.
openssl/openssl@71ed0fc

This commit fixes the following test failure in OpenSSL 4.0 FIPS by changing
testing password length from 6 to 8..

```
1) Error: test_private_encoding_encrypted(OpenSSL::TestPKeyRSA): OpenSSL::PKey::PKeyError: i2d_PKCS8PrivateKey_bio: encrypt error
/home/runner/work/openssl/openssl/test/openssl/test_pkey_rsa.rb:465:in `private_to_der'
/home/runner/work/openssl/openssl/test/openssl/test_pkey_rsa.rb:465:in `test_private_encoding_encrypted'
     462:
     463:   def test_private_encoding_encrypted
     464:     rsa = Fixtures.pkey("rsa2048")
  => 465:     encoded = rsa.private_to_der("aes-128-cbc", "abcdef")
     466:     asn1 = OpenSSL::ASN1.decode(encoded) # PKCS #8 EncryptedPrivateKeyInfo
     467:     assert_kind_of OpenSSL::ASN1::Sequence, asn1
     468:     assert_equal 2, asn1.value.size
Error: OpenSSL::PKey::PKeyError: i2d_PKCS8PrivateKey_bio: encrypt error
```

(cherry picked from commit 69f8cd1)

Author: junaruga

test/openssl/test_pkey_rsa.rb

@@ -529,53 +529,54 @@ def test_private_encoding
 
   def test_private_encoding_encrypted
     rsa = Fixtures.pkey("rsa2048")
-    encoded = rsa.private_to_der("aes-128-cbc", "abcdef")
+    encoded = rsa.private_to_der("aes-128-cbc", "abcdefgh")
     asn1 = OpenSSL::ASN1.decode(encoded) # PKCS #8 EncryptedPrivateKeyInfo
     assert_kind_of OpenSSL::ASN1::Sequence, asn1
     assert_equal 2, asn1.value.size
     assert_not_equal rsa.private_to_der, encoded
-    assert_same_rsa rsa, OpenSSL::PKey.read(encoded, "abcdef")
-    assert_same_rsa rsa, OpenSSL::PKey.read(encoded) { "abcdef" }
+    assert_same_rsa rsa, OpenSSL::PKey.read(encoded, "abcdefgh")
+    assert_same_rsa rsa, OpenSSL::PKey.read(encoded) { "abcdefgh" }
     assert_raise(OpenSSL::PKey::PKeyError) { OpenSSL::PKey.read(encoded, "abcxyz") }
 
-    encoded = rsa.private_to_pem("aes-128-cbc", "abcdef")
+    encoded = rsa.private_to_pem("aes-128-cbc", "abcdefgh")
     assert_match (/BEGIN ENCRYPTED PRIVATE KEY/), encoded.lines[0]
-    assert_same_rsa rsa, OpenSSL::PKey.read(encoded, "abcdef")
+    assert_same_rsa rsa, OpenSSL::PKey.read(encoded, "abcdefgh")
 
-    # certtool --load-privkey=test/openssl/fixtures/pkey/rsa2048.pem --to-p8 --password=abcdef
+    # Use openssl instead of certtool due to https://gitlab.com/gnutls/gnutls/-/issues/1632
+    # openssl pkcs8 -in test/openssl/fixtures/pkey/rsa2048.pem -topk8 -v2 aes-128-cbc -passout pass:abcdefgh
     pem = <<~EOF
-    -----BEGIN ENCRYPTED PRIVATE KEY-----
-    MIIFOTBjBgkqhkiG9w0BBQ0wVjA1BgkqhkiG9w0BBQwwKAQSsTIsinrhNMr4owUz
-    cwYGgB0lAgMJJ8ACARAwCgYIKoZIhvcNAgkwHQYJYIZIAWUDBAECBBDtDYqmQOLV
-    Nh0T0DslWgovBIIE0ESbJey2Pjf9brTp9/41CPnI9Ev78CGSv8Ihyuynu6G7oj7N
-    G7jUB1pVMQ7ivebF5DmM0qHAix6fDqJetB3WCnRQpMLyIdq5VrnKwFNhwGYduWA5
-    IyaAc4DHj02e6YLyBTIKpu79OSFxLrnLCRaTbvZIUQaGhyd6pB7iAhqz5YBC0rpa
-    iMK5TRlNGPYG9n2eGFOhvUsbJ4T8VDzjpVWw0VNRaukXtg4xiR6o1f0qSXqAb5d9
-    REq5DfaQfoOKTV9j7KJHDRrBQG81vkU4K+xILrCBfbcYb82aCoinwSep9LC30HaH
-    LZ0hYQOuD/k/UbgjToS2wyMnkz75MN5ZNhDMZl/mACQdsMMtIxG37Mpo1Ca33uZi
-    71TCOEKIblZS11L1YhIni9Af8pOuHJBWwezP2zN2nPwV6OhgL7Jlax7ICQOPC6L/
-    yRGgC5eT4lDDAuTy0IdUhr0r5XrFzZR0/5Vgsq9cGfk9QkXOoETRhQVkEfUDdCs6
-    6CK+SwUR9qh5824ShODFG0SQpsqBPIVtkGrypBSUJtICmGMOAsclB7RDN7/opJwp
-    qv/iRJ5dhWrhRgQ/DfYifvO5On7RgC2hm48gF3Pt6XCA857ryyYxLYeMY42tAUqp
-    Hmc9HL7bMYF/jl3cJ32+gLvI3PBVvrvyeAhRo6z7MFVe9I04OywV6BHUx1Us6ybF
-    qkYnSpcJZdu7HyvzXm7XWLFmt7K5BlAgnFsa/8+cI1BGPgQRc1j0SWepXsSwFZX6
-    JkNQ0dewq4uRJXbGyQgfh5I5ETpqDhSt2JfBwAoze6cx3DPC711PUamxyWMiejs+
-    mYdia4p62NxaUvyXWmCGIEOzajRwywEhf9OLAmfqTN41TIrEL4BUxqtzDyw8Nl8T
-    KB7nJEC366jFASfumNQkXXyH5yBIF+XwwSKUOObRZVn2rUzFToo51hHu9efxHoXa
-    jZlpfglWijkmOuwoIGlGHOq8gUn76oq9WbV+YO+fWm/mf4S3ECzmYzxb6a1uCTy/
-    Itkm2qOe3yTM1t+oCqZ0/MeTZ84ALQaWv5reQfjronPZ1jeNtxrYz28tJ4KwBn0U
-    bJReXbOLsHAymipncxlmaevbx4GPTduu/lbpxefoN95w+SpEdyTmVWrfaCTgAbad
-    EzcRl60my3xOMQ7CaUbRgGiwohqHDvuXzeqoZ96u6CwfAoEfy4jETmKLRH6uTtj7
-    4jdTyoqyizjpvaM8LPspBS+oqFwLxBjpseQuScrZO1BjPxrImLy2/VRqwJ+CF4FB
-    iijEgDgDc1EMIGe5YmOAV+i22n9RqX+2IvkYp7CWXrB9/lmirLFukd7hT8DLPUGq
-    AvSZwTPbDPoZKG3DAebC3DbiC7A3x0KZp24doNRLamZ/MyKHo2Rzl0UhkzDU0ly2
-    eAnyNYsOAQck+C6L+ieD95Gksm9YJWurwttm5JragbIJwMCrsBQd4bXDkKdRhxS2
-    JpS0dT/aoDmgTzoG07x4cZk0rjBkfX1ta0j0b1lz7/PZXl9AbRvFdq5sJpmv4Ryz
-    S+OERqo4IEfJJq2WJ92WR+HLGV3Gvsdb7znZTEF1tp4pWOLAt83Pry282UJxO7Pe
-    ySf/868TEmXams06GYvH+7cMiIT2m9Dc+EFgNaPmm0uMmJ+ZjqHKSOLzrL7C
-    -----END ENCRYPTED PRIVATE KEY-----
+-----BEGIN ENCRYPTED PRIVATE KEY-----
+MIIFNTBfBgkqhkiG9w0BBQ0wUjAxBgkqhkiG9w0BBQwwJAQQ+Sg92Hgy8EgVPf7t
+Hen1qwICCAAwDAYIKoZIhvcNAgkFADAdBglghkgBZQMEAQIEEB5UX2xdDO8/AKA8
++Y5CZyUEggTQkArh4mMPpnAe3xOcDKMz8KCn5lrLb/6Dla7Rp9LHKGkUfyI11EZt
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+jGvHjeMoVx3rZXHcZDAzfIZvDigp9uAfzjRJjpRG8sg5sDQVC7vdUhQDe5TorKT2
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+BeIcUcMLsDHayIaQaMLIftHxOkfX7UxoFW9CMG5UMQf/m3eEgVUwgK/E5sUJRUTo
+yhRzJ4NAP4fgc4YH9tbzvUrhfdCXCBEOn6IlDQL66SZr8Mm+Ggu4Ij4TnKWXLrXL
+nSTDDa42kPOvtedKqxC/uXE7rrfh+uyw6J6OjSl6u86TIebndLuDo5DTdWKh8rsg
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+/HP4drWamLWYJR8FsmJS11ZYc1EK/ctJTSpqfewvoUGOSHomhh7zXn1Acb6+9/3p
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+iJxwrrvSgQPmOGuxrh5LVD41UXYUWLtndzabnpByppFn2MbmvrqJgon0MSs84cTA
+7scnbPu1V3PpKy/t67gtVw9Ue8hLjrskWB1JPFYr7vRWvJzYjfbflyroF+QEJ3TA
+6rTfUC9+ePci6T+i9jF4xcmzqYzRtnGtp5nRUitJGw0uwBTDwzfI2WD6ltvvu7lc
+pHuzvY5zEapuu1JhjHLUd+OE8rVVM999DUXo/IDLsWyRCphCiYfVXJNogd9rB0Ta
+5AhVgpRhxkarBURZyLTYj7NRxCsbHq7XExJNrIdRG/KlBQfyEyIzZ7E=
+-----END ENCRYPTED PRIVATE KEY-----
     EOF
-    assert_same_rsa rsa, OpenSSL::PKey.read(pem, "abcdef")
+    assert_same_rsa rsa, OpenSSL::PKey.read(pem, "abcdefgh")
   end
 
   def test_dup