tcm_node: Tidy and shorten some functions, part 1
tcm_node: Tidy and shorten some functions, part 1

Functions:
tcm_add_alua_tgptgp
tcm_alua_check_metadata_dir
tcm_alua_delete_metadata_dir

Prefer Python built-in function, rather than using os.system.
Use os.rmdir() instead of os.system

Signed-off-by: Andy Grover <b7d524d2f5cc5aebadb6b92b08d3ab26911cde33@redhat.com>
Signed-off-by: Nicholas A. Bellinger <978acd1567d5598152161fdf8bf3ca568f950c9b@linux-iscsi.org>

Datera/lio-utils,Datera/lio-utils,Datera/lio-utils,Datera/lio-utils