Remove use of FnvHashMap/Set for queue IDs and client IDs

[guilload]

It's only good for really short strings (< 20 bytes), but our strings are not that short:

• node IDs are not that short:quickwit-indexer-prod-us-east-1a
• index UIDs are not that short: logline.c06d8f1aee.2024-02-01.10:01HNGZE70MS3YBV8FVSMVTA910
• queue IDs are not that short: <index_uid>/<source_id>/<shard_uid>

Let's revert to the default HashMap/Set.

[fulmicoton]

This is not a bug, so I removed the tag.

Also this bench suggests the limit where HashMap overperforms FnvHashMap is at around 60bytes.
https://cglab.ca/~abeinges/blah/hash-rs/
I'd rather stick to FnvHashMap for the moment.