tests: housekeeping, test_ldap.py

housekeeping, the following is looked at and may have been done:
* fixed typos and standardized formatting
* renamed test cases to improve the clarity of what the test does
* improved docstring language, setup, steps and expected results
* synced code with the docstring order
* removed necessary configuration relevant to the test
* added pytest.mark.importance to test cases

noteable changes:
* removed lookup_user_default_naming_context_and_no_search_base because it is already covered by another test scenario
added description to ppolicy tests, providing an explanation
* removed enumeration configuration from tests where enumeration is not being tested
* removed test case checking log messages for timeout

Reviewed-by: Alejandro López <[email protected]>
Reviewed-by: Anuj Borah <[email protected]>
Reviewed-by: Shridhar Gadekar <[email protected]>
(cherry picked from commit 8c19d7b)