This is a race condition specific to this test. Outside of this test, we shut down replication before killing index builds.

The race condition is as follows:

• Kill the index build by aborting without cleanup
• Process a commitIndexBuild oplog entry, which attempts to restart the index build. The index is ready:false on disk, which leads to a "Cannot build two identical indexes" error message by the applier thread.

This test may be able to be rewritten without the "leaveIndexBuildUnfinishedForShutdown"  failpiont that violates shutdown ordering.