create_if_missing doesn't always take effect

In the logs we see:

```
[warning] 2022-12-01T06:27:19.402535Z couchdb@couchdb-couchdb-1.couchdb-couchdb.drive-app.svc.cluster.local <0.1954.0> -------- mem3_sync shards/00000000-7fffffff/manifests-0038211.1669809395 couchdb@couchdb-couchdb-0.couchdb-couchdb.drive-app.svc.cluster.local {{rexi_EXIT,{{error,missing_target},[{mem3_util,get_or_create_db,2,[{file,[115,114,99,47,109,101,109,51,95,117,116,105,108,46,101,114,108]},{line,525}]},{mem3_rpc,load_checkpoint_rpc,4,[{file,[115,114,99,47,109,101,109,51,95,114,112,99,46,101,114,108]},{line,122}]},
```

load_rpc_checkpoint https://github.com/apache/couchdb/blob/f13ceb46ce3c120e1960fa47bfda0a606601900e/src/mem3/src/mem3_rpc.erl#L107-L110

calls get_or_create
https://github.com/apache/couchdb/blob/f13ceb46ce3c120e1960fa47bfda0a606601900e/src/mem3/src/mem3_util.erl#L606-L612

And there oddly enough, even with a `[{create_if_missing, true}]` we still catch `error:database_does_not_exist` error.

It could be from trying to load validation functions, security, shard doc, design docs or something of that type which blows up.

Perhaps?

https://github.com/apache/couchdb/blob/f13ceb46ce3c120e1960fa47bfda0a606601900e/src/couch/src/couch_db.erl#L977-L979

But I don't see how'd call that from this context: https://github.com/apache/couchdb/blob/f13ceb46ce3c120e1960fa47bfda0a606601900e/src/couch/src/couch_server.erl#L108-L129

Start with the linked paths in src/mem3/src/mem3_rpc.erl and src/mem3/src/mem3_util.erl, especially load_rpc_checkpoint and get_or_create. Trace how create_if_missing is passed and where database_does_not_exist is raised, then inspect the referenced couch_db.erl and couch_server.erl sections. Done means identifying why the option is not honored and adding a regression test for the missing-target case.

Written by the indexing model from the issue text.