Coverity static analysis: Synchronization on java.util.concurrent object in ElytronPolicyConfigurationFactory

Coverity static-analysis scan found a synchronization on java.util.concurrent.ConcurrentHashMap object in:

• ElytronPolicyConfigurationFactory.getPolicyConfiguration
• ElytronPolicyConfigurationFactory.inService

If policyConfiguration synchronization is concern, it should be enough to synchronize on policyConfiguration object.

https://scan7.coverity.com/reports.htm#v23632/p11778/fileInstanceId=8490244&defectInstanceId=2123208&mergedDefectId=1377483
https://scan7.coverity.com/reports.htm#v23632/p11778/fileInstanceId=8490244&defectInstanceId=2123209&mergedDefectId=1377485