This removes the dependency on shared libmonosgen installed locally
and makes the artifacts usable as standalone for testing without
needing a full Mono install.
This was forgotten when renaming 3.2.4 to 3.3.
Once 3.3-stable is out and we branch off to 3.3, the BASE_BRANCH should
be bumped to 3.3 in that branch.
We often hit "Too Many Requests" errors when uploading the cache with
`actions/cache` because there's a limit of 10 GB every 5 minutes, and we can
easily go over it when we amend or merge several PRs in a short timespan.
This will make the CI artifacts less useful for debugging crashes but there's
no real way around this.
(cherry picked from commit caea551d41)
