Optimise queue index initialisation

Avoid loading the journal when the file doesn’t exist.
Also try to avoid flushing the journal unless necessary.
merge default into bug25853
merge default into bug25853
merge default into bug25853
containing the recently merged bug25827
Perform (and wait for) queue recovery in parallel
Simplify durable queue recovery and avoid a dict lookup on the results
Use dirty opts to find durable queues during startup (and optimise)
simplifying refactor
rename misleading variables
...and fix a counting error
cosmetic
merge default into bug25853
oops
rabbit_file:wildcard/2 should return [] if the dir is non-existing
merge default into bug25853
since the previous merge pulled in a breakage
merge bug25853 into default