Remove unused appointments feature toggles - 2

[JunTaoLuo]

Are you removing, renaming or moving a folder in this PR?

• No, I'm not changing any folders (skip to TeamSites and delete the rest of this section)
• Yes, I'm removing, renaming or moving a folder

⚠️ TeamSites ⚠️

Examples of a TeamSite: https://va.gov/health and https://benefits.va.gov/benefits/. This scenario is also referred to as the "injected" header and footer. You can reach out in the #sitewide-public-websites Slack channel for questions.

Did you change site-wide styles, platform utilities or other infrastructure?

• No
• Yes, and I used the proxy-rewrite steps to test the injected header scenario

Summary

• Removing some of the obsolete feature toggles for unused features.
• Note that va_online_scheduling_use_dsot is not defined or used in vets-website so there's no reference to it in this PR. It will be removed from vets-api in a separate PR.
• Appointments tools team

Related issue(s)

• VAOS feature toggle cleanup - part 2 va.gov-team#103685

Testing done

• Ensured existing test suites pass

Screenshots

N/A

What areas of the site does it impact?

Appointments tools

Acceptance criteria

Quality Assurance & Testing

• I fixed|updated|added unit tests and integration tests for each feature (if applicable).
• No sensitive information (i.e. PII/credentials/internal URLs/etc.) is captured in logging, hardcoded, or specs
• Linting warnings have been addressed
• Documentation has been updated (link to documentation *if necessary) Will update documentation after PRs are merged and feature toggles fully deleted from Flipper
• Screenshot of the developed feature is added
• Accessibility testing has been performed

Error Handling

• Browser console contains no warnings or errors.
• Events are being sent to the appropriate logging solution
• Feature/bug has a monitor built into Datadog or Grafana (if applicable)

Authentication

• Did you login to a local build and verify all authenticated routes work as expected with a test user