Clean up more the output of `convert_docx_to_markdown`

[samarth9008]

The doc for the flow is here docs/documentation_meta/all.gdocs.how_to_guide.md

The script is here dev_scripts/documentation/convert_docx_to_markdown.py

• [x] Convert a Gdoc file into a markdown - https://docs.google.com/document/d/1vg2IipQ4csA18hv041uRjxyF_vcdHrWuhpejf2zhaUs/edit

• [ ] Merge it and remove the Gdoc

• [x] Add unit tests for the script -

• [x] Extend the script to handle a few corner cases

Remove - [<span class="underline">Google Authenticator</span>]
Remove - 
[<u>Google Authenticator</u>]
… (one char) -> …

Remove the style `<img src="figs/setup_vpn_and_dev_server_access/image1.png" style="width:5.43272in;height:4.52727in" />`

I would focus on one thing at a time. Start with something easy and have multiple PRs to achieve the goal to ease up the review

FYI @gpsaggese @sonaalKant