Remove on-by-default go_user_delete_{branch,tag} feature flags
As in fbc9f83a (Remove Ruby code for 100% on user_delete_{branch,tag} in Go feature, 2021-01-15) remove the old Ruby code, but this time for the Ruby user_create_{branch,tag} code.
These features have been on in production since 2021-01-14: #3412 (comment 485304117) #3413 (comment 485303898)
I'm removing more code than I did in fbc9f83a per a comment from @toon: !3010 (comment 488175228)
This brings the runtime of:
time go test -v ./internal/gitaly/service/operations/ -run 'Tag|Branch' -count=1
From ~25 seconds to ~15 second.
Edited by Ævar Arnfjörð Bjarmason