clean up RELEASE_ACONFIG_VALUE_SETS

Only add a repository to the trace when it actually specifies
aconfig_value_sets.

Also default to only generating the release config .mk file for the
current TARGET_RELEASE (rather than all), to reduce kati reruns.

Bug: 340126861
Test: manual, TH
Change-Id: I671d4b5f57c9bdd252d98e048f16aa9c7b3b2ffa