Investigate if IdTokenCredential needs to query MDS service for service account email #1772
Description
Currently ID token credentials makes this call here:
google-auth-library-python/google/auth/compute_engine/credentials.py to query service_account_info, however I am not sure if this call is needed because each gce instance can only have 1 service account, therefore getting id token credential with "default" email address should also work.