MX-1280, Miscellaneous test fixes:
remove replUndoOplogEntry from test_all_commands.js
add getLastError after writes in fastUpdatePKForShard.js
fix rollback_after_removed_docs.js, make gleGTID.js more robust
add partition_stats2.js as an exception to sharding_passthrough
fix consensus.js to be more robust
small fix for opReplicatedEnough
Merge branch 'master' into 2.0-pre