Esha's investigation as part of WRITING-10501 discovered that voteCommitIndexBuild is not blocked by tenant access blockers, so index builds might hang forever waiting for quorum which never arrives. The best solution would be to leverage tenant access blockers to block voteCommitIndexBuild commands, but that work is very involved. As a stop-gap, the server should abort in-progress index builds before starting a shard split operation similar to tenant migrations.