[MS-40426] Improve Code Coverage % for Azure

• issue Reference: osdu/platform/ci-cd-pipelines#40
• refactored the existing testcases to run on Junit5
• added missing testcases scenarios/branches for
  • MdcContextMap.java
  • RecordsChangedSbMessageBuilder.java
  • ServiceAccountJwtClientImpl.java
  • AbstractRecordChangedMessageHandlerWithActiveRetry.java
  • MetricService.java
• updated 'jacoco-maven-plugin' configuration exclusion list [SpringBootApplication class & Configuration classes/packages]
• Azure Code Coverage Report Current MR with 85% vs master with 75%