[Docs] Don't include unittest documentation

The `test_quota` and `test_policy` modules
don't need to be documented, since they present
no meaningful information to contributors.

Removing these also avoids the docstring
formatting issues that ddt may introduce
to the sphinx build. [1]

[1] datadriventests/ddt#51

Change-Id: I8136e8a000e04bcc213a746c7d793bf9373b1b38
Closes-Bug: #1783124

doc/source/contributor/auth.rst

@@ -39,29 +39,6 @@ The :mod:`manila.policy` Module
     :undoc-members:
     :show-inheritance:
 
-
-Tests
------
-
-The :mod:`test_quota` Module
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. automodule:: manila.tests.test_quota
-    :noindex:
-    :members:
-    :undoc-members:
-    :show-inheritance:
-
-The :mod:`test_policy` Module
-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-
-.. automodule:: manila.tests.test_policy
-    :noindex:
-    :members:
-    :undoc-members:
-    :show-inheritance:
-
-
 System limits
 -------------