Make sure ix-apps mountpoint is correct (#14937)

If a user downgrades to DF or earlier and he had ix-apps dataset, and he comes back to EE or later, what will happen is that the mountpoint for ix-apps would be reset because of the logic we have in place to reset any custom mountpoints any user might have. So changes have been added to ensure that ix-apps dataset always has a consistent mountpoint set because then EE or later can treat it as apps dataset (if apps are configured) which will result in various errors as it would not be mounted where we want it to be mounted

src/middlewared/middlewared/plugins/pool_/import_pool.py

@@ -3,6 +3,7 @@
 import os
 import subprocess
 
+from middlewared.plugins.docker.state_utils import IX_APPS_DIR_NAME
 from middlewared.schema import accepts, Bool, Dict, List, returns, Str
 from middlewared.service import CallError, InstanceNotFound, job, private, Service
 
@@ -133,6 +134,13 @@ async def import_pool(self, job, data):
                 # We exclude `ix-applications` dataset since resetting it will
                 # cause PVC's to not mount because "mountpoint=legacy" is expected.
                 # We exclude `ix-apps` dataset since it has a custom mountpoint in place
+                # If user downgrades to DF or earlier and he had ix-apps dataset, and he comes back
+                # to EE or later, what will happen is that the mountpoint for ix-apps would be reset
+                # because of the logic we have below, hence we just set and it's children will inherit it
+                if child == os.path.join(pool_name, 'ix-apps'):
+                    await self.middleware.call(
+                        'zfs.dataset.update', child, {'properties': {'mountpoint': {'value': f'/{IX_APPS_DIR_NAME}'}}}
+                    )
                 continue
             try:
                 # Reset all mountpoints