fix: clear cache before testCachePurged to prevent stale entry interference

AzureAppConfigurationProviderTest#testCachePurged was failing on CI
because the static OracleConfigurationCache could hold valid credentials
from a previous test run, causing the first connection to succeed from
cache instead of fetching the (intentionally wrong) credentials from
Azure App Config. Added @BeforeAll to obtain the cache reference and
a CACHE.remove() call at the start of the test, mirroring the pattern
already used in AzureAppConfigurationProviderURLParserTest.

Author: elaaissaouiabdessamad

ojdbc-provider-azure/src/test/java/oracle/jdbc/provider/azure/configuration/AzureAppConfigurationProviderTest.java

@@ -8,7 +8,10 @@
 import oracle.jdbc.provider.TestProperties;
 import oracle.jdbc.provider.azure.AzureTestProperty;
 import oracle.jdbc.provider.azure.authentication.AzureAuthenticationMethod;
+import oracle.jdbc.spi.OracleConfigurationProvider;
+import oracle.jdbc.util.OracleConfigurationCache;
 import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
 
@@ -21,6 +24,16 @@
 
 class AzureAppConfigurationProviderTest {
 
+  private static OracleConfigurationCache CACHE;
+
+  @BeforeAll
+  static void init() {
+    OracleConfigurationProvider.allowedProviders.add("azure");
+    CACHE = ((AzureAppConfigurationProvider) OracleConfigurationProvider
+        .find("azure"))
+        .getCache();
+  }
+
   /**
    * Label-related tests
    */
@@ -113,6 +126,9 @@ public void testCachePurged() throws SQLException {
 
     String url = composeUrlWithServicePrincipleAuthentication(originalUrl);
 
+    // Clear cache to ensure we fetch fresh credentials from Azure App Config
+    CACHE.remove(APP_CONFIG_NAME + "?key=" + APP_CONFIG_KEY + "&label=" + APP_CONFIG_LABEL);
+
     // Retrieve original value of 'user'
     String originalKeyValue =
       client.getConfigurationSetting(APP_CONFIG_KEY + username,