[Develop] Add internal shared directories to the list of reserved directories for the SharedStorageMountDirValidator. (#5779)

Author: dreambeyondorange

cli/src/pcluster/validators/cluster_validators.py

@@ -914,6 +914,11 @@ def _validate(self, mount_dir: str):
             "/media",
             "/mnt",
             "/opt",
+            "/opt/parallelcluster",
+            "/opt/parallelcluster/shared",
+            "/opt/parallelcluster/shared_login_nodes",
+            "/opt/slurm",
+            "/opt/intel",
             "/proc",
             "/root",
             "/run",