Re-home adhoc cloned servers to the calling user

When /misc/workspace/adhoc_connect_server is given a sid, it clones the
existing server. Server.clone() copies every column of the source row,
including user_id, shared and shared_username. When a non-owner triggered
an adhoc connect against an administrator-owned shared server, the clone
inherited the administrator's ownership and shared flag, so pgAdmin
persisted a new, administrator-owned, shared adhoc server row created at
the behest of another user; the row is committed before the connection is
attempted, so it survived even when the connection failed.

Force the cloned adhoc record to belong to the current user and to be
private (user_id, shared, shared_username) before committing, mirroring
the new-server branch, so a non-owner can no longer persist a
cross-tenant server record.

web/pgadmin/misc/workspaces/__init__.py

@@ -176,6 +176,17 @@ def adhoc_connect_server():
                 # Clone the server object
                 server = server.clone()
 
+                # Server.clone() copies every column from the source row,
+                # including user_id/shared/shared_username. When the source
+                # is another user's shared server, the clone must not inherit
+                # that ownership: force the new adhoc record to belong to the
+                # current user and to be private, otherwise a non-owner ends
+                # up persisting a cross-tenant, administrator-owned server
+                # row.
+                server.user_id = current_user.id
+                server.shared = False
+                server.shared_username = None
+
                 # Replace the following with the new/changed value.
                 server.maintenance_db = new_db
                 server.username = new_username