Move --plugins to within _repoquery()

This ensures that all repoquery commands use --plugins. Fixes #14789.
Add plugins to group_info() repoquery calls

The calls here do not use the _repoquery() helper function and need to
have --plugins added to them.
Merge pull request #14811 from terminalmage/backport-issue14789-to-2014.1

Backport #14810 to 2014.1 branch