Remove BigDecimal_divremain(which has a bug) and use BigDecimal_DoDiv… #474

Job	Run time
ruby-versions / Generate Ruby versions	5s
ubuntu-latest 2.7	1m 6s
ubuntu-latest debug	46s
ubuntu-latest 3.0	32s
macos-latest 2.7	58s
ubuntu-latest 3.2	40s
macos-latest 3.3	23s
ubuntu-latest head	38s
ubuntu-latest 3.4	39s
ubuntu-latest 3.3	40s
ubuntu-latest 3.1	34s
macos-14 2.7	1m 10s
macos-latest debug	36s
macos-latest 3.1	38s
macos-14 3.1	38s
macos-latest 3.0	27s
macos-14 3.0	28s
macos-14 3.3	25s
macos-latest 3.4	29s
macos-14 head	29s
macos-latest head	27s
macos-14 3.2	24s
macos-latest 3.2	28s
windows-latest 3.3	3m 39s
macos-14 3.4	22s
windows-latest mswin	3m 16s
windows-latest 2.7	6m 3s
windows-latest 3.4	4m 2s
windows-latest head	3m 57s
macos-14 debug	39s
windows-latest mingw	3m 33s
	39m 11s

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