renaming a timeseries bucket collection is currently allowed (under special priviledges) and also used internally by $out.

The problem is that when we execute a rename of a timeseries bucket collection we do not check if a collection already exist on the target main namespace.

For instance, if we do the following:

db.createCollection( 'srcColl', { timeseries: { timeField: "timestamp", metaField: "metadata" } })
db.createCollection( 'dstColl')
db.system.buckets.srcColl.renameCollection(system.buckets.dstColl);

The rename should fail because the target collection already exists and instead it works leaving the local catalog with both normal collection 'db.dstColl' and timeseries bucket collection 'db.system.buckets.dstColl'

We should extend jstests/core/rename_system_buckets_collections.js to cover those scenarios.