Enable E121,E122,E123,E124,E125,E129 flake8 tests

Enable the tests and update flake8 comments to note that H904 is ignored
on purpose.

The patch fixes these warnings:
./manila/api/views/limits.py:68:5: E129 visually indented line with same
    indent as next logical line
./manila/share/drivers/netapp/cluster_mode.py:352:13: E122 continuation
    line missing indentation or outdented
./manila/scheduler/scheduler_options.py:98:13: E129 visually indented
    line with same indent as next logical line
./contrib/tempest/tempest/api/share/base.py:210:5: E129 visually
    indented line with same indent as next logical line
./contrib/tempest/tempest/api/share/test_rules.py:32:13: E129 visually
    indented line with same indent as next logical line
./contrib/tempest/tempest/api/share/test_rules.py:90:13: E129 visually
    indented line with same indent as next logical line
./manila/api/views/share_servers.py:28:9: E124 closing bracket does not
    match visual indentation
./manila/api/views/share_servers.py:34:9: E124 closing bracket does not
    match visual indentation
./manila/share/drivers/netapp/driver.py:336:5: E125 continuation line
    with same indent as next logical line

Also fixes other pep8 warnings in these files.

Partial-Fix: #1333290

Change-Id: Ida14ea8f4716e49f7379f929971fd5e462541527