ref: Simplify GroupTagValueSerializer logic (#6223)
ref: Simplify GroupTagValueSerializer logic (#6223)

First, there was dead code related to user_lookups that I forgot to
remove before.

Second, the only label we support for TagValues are for
'sentry:release', so that query can be removed and the logic can be
greatly simplified.

In the future I will move the label-ification block into the tagstore
abstraction so it won't be in such a weird spot.
beeftornado/sentry,beeftornado/sentry,mvaled/sentry,mvaled/sentry,mvaled/sentry,gencer/sentry,ifduyue/sentry,looker/sentry,looker/sentry,ifduyue/sentry,mvaled/sentry,ifduyue/sentry,beeftornado/sentry,gencer/sentry,ifduyue/sentry,gencer/sentry,mvaled/sentry,looker/sentry,looker/sentry,looker/sentry,gencer/sentry,gencer/sentry,mvaled/sentry,ifduyue/sentry