Use debug logging instead for Azure tests (#44672)

These Azure tests have hard println statements which means we always see
these messages during configuration. Yet, there are unnecessary most of
the time. This commit changes them to use debug logging.

plugins/repository-azure/qa/microsoft-azure-storage/build.gradle

@@ -70,11 +70,11 @@ testClusters.integTest {
     plugin file(project(':plugins:repository-azure').bundlePlugin.archiveFile)
     keystore 'azure.client.integration_test.account', azureAccount
     if (azureKey != null && azureKey.isEmpty() == false) {
-        println "Using access key in external service tests."
+        logger.debug("Using access key in external service tests.")
         keystore 'azure.client.integration_test.key', azureKey
     }
     if (azureSasToken != null && azureSasToken.isEmpty() == false) {
-        println "Using SAS token in external service tests."
+        logger.debug("Using SAS token in external service tests.")
         keystore 'azure.client.integration_test.sas_token', azureSasToken
     }
 
@@ -87,6 +87,6 @@ testClusters.integTest {
         String firstPartOfSeed = project.rootProject.testSeed.tokenize(':').get(0)
         setting 'thread_pool.repository_azure.max', (Math.abs(Long.parseUnsignedLong(firstPartOfSeed, 16) % 10) + 1).toString(), System.getProperty('ignore.tests.seed') == null ? DEFAULT : IGNORE_VALUE
     } else {
-        println "Using an external service to test the repository-azure plugin"
+        logger.debug("Using an external service to test the repository-azure plugin")
     }
 }