Reconcile sidebar titles with mission index page titles

[jaladh-singhal]

Now that we are generating notebook gallery from notebook_metadata.yml (#298), some of the short notebook titles are out of sync with the titles we have in the sidebar from toc.yml

We have 5 mission index pages, following notebooks' short tiles mismatch:

1. SPHEREx: None
2. Euclid:
   • almost half of the notebooks
   • HATS notebook will require special handling since they are nested
3. WISE:
   • AllWISE Source Catalog,
   • NEOWISE Solar System Objects
4. Simulated Data: None
5. Techniques & Tools:
   • HATS with LSDB