Object Store tests hang in github CI

The zfs-object-agent service is used by ZTS, but that service depends
on the zfs-mount service, which isn't enabled by the package install
done by CI. This causes the agent to fail to start, and the rest of the
test run hangs. By enabling and starting zfs-mount prior to launching
the tests, the agent can successfully start.

.github/workflows/zfs-tests-object-store.yml

@@ -62,6 +62,12 @@ jobs:
         sudo cp -r $HOME/.aws /root
     - name: Tests
       run: |
+        # The github CI package build doesn't enable any ZFS services by
+        # default. Since the object agent service is available on the test VM,
+        # ZTS tries to use it. Since it depends on the zfs-mount service, we
+        # enable it here. If we don't the agent will fail to start, and the
+        # workflow will hang.
+        sudo systemctl enable --now zfs-mount
         /usr/share/zfs/zfs-tests.sh -v -s 3G -r object_store
       env:
         LD_LIBRARY_PATH: /lib/x86_64-linux-gnu