Clean up deprecated ENVs

[tom2drum]

Description and Related Issue(s)

Removed the following environment variables from the code because they are no longer supported:

• NEXT_PUBLIC_ROLLUP_PARENT_CHAIN_NAME
• NEXT_PUBLIC_SENTRY_DSN
• SENTRY_CSP_REPORT_URI
• NEXT_PUBLIC_SENTRY_ENABLE_TRACING
• NEXT_PUBLIC_AUTH0_CLIENT_ID
• NEXT_PUBLIC_AUTH_URL
• NEXT_PUBLIC_LOGOUT_URL
• NEXT_PUBLIC_RE_CAPTCHA_V3_APP_SITE_KEY
• NEXT_PUBLIC_HOMEPAGE_PLATE_TEXT_COLOR
• NEXT_PUBLIC_HOMEPAGE_PLATE_BACKGROUND

Checklist for PR author

• I have tested these changes locally.
• I added tests to cover any new functionality, following this guide
• Whenever I fix a bug, I include a regression test to ensure that the bug does not reappear silently.
• If I have added, changed, renamed, or removed an environment variable
  • I updated the list of environment variables in the documentation
  • I made the necessary changes to the validator script according to the guide
  • I added "ENVs" label to this pull request