Remove tooltip manager to get tests working in CMS again.

My theory is that the discussion module tooltip_manager is not getting bundled into the "xmodule" JS. It would work locally if the non-bundled file can be found.

To fix this, we should really move the toolitp_manager to the correct location. In the short term, I think it is OK to just remove the dependency. Tooltips won't work, but they didn't for large parts of CMS before Anton's PR anyway.

@polesye here is a pointer to how we bundle JS in common package for use by RequireJS in CMS (since it is not used in LMS nor in common in general). Take a look at /edx-platform/common/djangoapps/pipeline_js/urls.py and /edx-platform/common/djangoapps/pipeline_js/templates/xmodule.js and /edx-platform/common/djangoapps/pipeline_js/views.py