Insert token prefix 'Bearer ' when it is missed
The IServiceAccountJwtClient.getIdToken() has inconsistent implementation: Impl of GCP/AWS returns token with prefix 'Bearer' while Impl of Azure/IBM returns token only.
Given the PartitionFeatureFlagImpl.java in the core common assumes that the method IServiceAccountJwtClient.getIdToken() returns a token with 'Bearer' prefix, the implementation of IServiceAccountJwtClient.getIdToken() for Azure/IBM in the indexer should return the token with 'Bearer' prefix.
Edited by Zhibin Mai