web: drop `bootstrap` depenedency

Created by: valerybugakov

Context

This PR removes bootstrap from package.json dependencies and updates documentation to reflect that we do not use bootstrap directly anymore.

Closes #29200 (closed)

Test plan

1. Check out the updated documentation.
2. Ensure that CI is green.
3. Ensure that bootstrap is not present in the lock file.

App preview:

• Web
• Storybook

Check out the client app preview documentation to learn more.