I've checked the spots when `Invitation::new()` and `Invitation::take()`
are used and it seems like all spots are already correctly gated. So to
enable invitations via admin API even when invitations are otherwise
disabled, this check can be removed.
This is done to enable backup functionality in the admin interface while
we're waiting for the libsqlite-sys 0.17 to bubble up in the upstream
dependencies. Then we can start using `VACUUM INTO`
This also extends the check for the sqlite binary to also try `sqlite3`
as this is the name of the binary in baseimage distributions we use.
This changes the healthcheck to use `sh` instead of bash, that is absent
from some image versions. (like alpine)
It also removes `*mariadb*` packages from runtime image of sqlite images
as these shouldn't be required.
Miro Prasil