Disable concurrency in tests while we work out the kinks

AC-408 converting video slider controls from a to div

Sstudent/tnl 4468

AC-413 adding labels to form fields on Instructor dashboard membership page

[EV-12] Run LMS unit tests concurrently on jenkins

Update translations (autogenerated message)

Ensure correct CSV headers for non-English

Support named-release translation files.

turn on bok choy XSS checking

The test TestComprehensiveTheming.test_themed_footer in lms/djangoapps/course_wiki/tests/test_comprehensive_theming.py
fails when run immediately after lms.djangoapps.course_wiki.tests.test_middleware:TestWikiAccessMiddleware.test_url_tranform.

Until we have a chance to fix it, we're going to skip it to expedite merging
concurrent testing.

To reproduce the failure, remove the @skip decorator, and run:

paver test_system -s lms --disable-migrations --test_id='lms.djangoapps.course_wiki.tests.test_middleware lms.djangoapps.course_wiki.tests.test_comprehensive_theming' --no-randomize -v --processes=0

WL-450 Fix for issue with canceling changes to image upload fields

Disable `Generate Exception Certificate button

Christina/mark flaky tests

Fix another kind of math problem which was overflowing

TNL-4566: Lint Mako templates outside of expressions

Exclude deleted files from safe template linting

SOL-1776 Added Studio settings image upload acceptance tests

clear request cache after celery task finishes (TNL-2705)

SOL-1811

- Lint directories and files in sorted order.
- Lint python blocks in Mako.

TNL-4590