Move group config to GNUPGHOME

Unlike the previous attempts this only moves the group config to
GNUPGHOME as these are the only one config which depends on the content
of the keyring.

This requires running the migrations before initializing the
application.

(cherry picked from commit 4db71fb8cd2806f42bd83f4ec7bf0d2f0c304c26)

• GnuPG-bug-id: T6931