refs: move parsing of "core.logAllRefUpdates" back into ref stores

refs: move parsing of "core.logAllRefUpdates" back into ref stores

In cc42c88945 (refs: extract out reflog config to generic layer,
2026-05-04) we have refactored how we parse "core.logAllRefUpdates" so
that it happens in the generic layer. Unfortunately, this has worsened a
preexisting issue where we may recurse when creating the reference store
because of a chicken-and-egg problem between parsing the configuration
and evaluating "onbranch" conditions.

Prepare for a fix by essentially reverting that change so that we handle
this setting in the respective backends again. The backends are already
parsing other configuration anyway, so by moving the logic back in there
we can ensure that all backend configuration is parsed the same way.

Signed-off-by: Patrick Steinhardt <redacted>
Signed-off-by: Junio C Hamano <redacted>