[3.1.9 backport] Collection appears to be linked to 2 DBs after update error

able to repro on 3.1.3 locally... # create db01 offline, with coll01

1. create db02 offline, with coll02
2. update db02 with coll01, coll02 , get a 409 Conflict error
3. then GET /_config?include_runtime=true , returns db02 with with both, coll01 and coll02  <--- ?!
4. but GET /db02/_config, returns correctly with coll02 only
5. and then, if you bring db02 online, it will fix return for GET /_config?include_runtime=true

File with commands is attached.