Replace the EC2 role provider with the default role provider to accomodate ECS
requested to merge kusuriya/gitlab-elasticsearch-indexer:47-Support-ECS-instance-profile-IAM-task-credentials into master
Closes #47 (closed) and is required as part of MR #24926 and to close the issue resolved by it.
This fix is a change to the clients credential provider to allow for use of the default remote credentials fetcher instead of the EC2 specific one. This will allow the indexer to grab both EC2 and ECS task credentials and allow for running the indexer in an ECS container
Edited by Changzheng Liu