The gate testing sets gerrit_database_type to 'h2', but the container
does not setup /var/gerrit/db. It ends up owned by root in the
container and gerrit can't write to it, causing traceback errors for
account_patch_reviews when anything is updated.
Add a db peer directory with the other config dirs, and make sure it
is bind mounted into the image in the same way.
While we are here, alphabetise this list of directories for
consistency.
Change-Id: Ib24e3027622a711db76d24172b27cdebe6152cb6
27c3f7ac1e