Replace 'colab' and 'binder' with 'Jupyterhub' in 'Launch' menu

[dulude]

Relevant Tickets and PRs

• Ticket SPB-1502
• PR Refactor notebook "Launch menu" items #51
• PR Reverted changes from PR #51 #52
• PR Fix bug preventing 'colab' and 'binder' launch menu buttons from opening Jupyter notebooks correctly #53

High-Level Summary

• The issue with mast_notebooks/ content not launching in TIKE was found to be a server-side issue that could be solved by removing an existing clone of the mast_notebooks in the virtual environment and that the changes in PR Reverted changes from PR #51 #52 could be reverted.

Summary of Changes

• Returned the launch buttons section of the _config.yml file back to the state post-PR Refactor notebook "Launch menu" items #51 merge.
  • Commented out 'binderhub_url' and 'colab_url' params in _config.yml.
  • Uncommented 'jupyterhub', 'jupyterhub_url' and 'notebook_interface' params in _config.yml.
• Commented out the 'path_to_book' param in _config.yml.
  • It was contaminating the URL used to launch notebooks in binder and colab leading to "notebook not found" errors.