Alert settings integration UX updates

What does this MR do?

A tiny MVC to account for any UX issues with the new Alert Settings integrations form.

This feature sits behind a feature flag: http_integrations_list for the frontend and multiple_http_integrations for the backend.

Design

Screenshots

This merge supports this Epic: &4442 (closed) and will come in the following stages:

Merge	You are here
Add initial wrapper for new form and feature flag	!45993 (merged)
Add GraphQL read endpoint to new form	!46212 (merged)
Build out HTTP and Prometheus steps for new form / Add GraphQL Add HTTP endpoint to new form	!46647 (merged)
Add GraphQL Update / Reset Token(Add GraphQL support for updating alert integrations) endpoint to new form	!46697 (merged)
Add GraphQL delete integration endpoints(backend here: !45843 (merged)	!46849 (merged)
Add ee support to add multiple endpoints	!46889 (merged)
Add row highlighting	!47001 (merged)
Test Payload	!47079 (merged)
Opsgenie	!47192 (merged)
UX Review	🤘
Abstraction/clean up	TBA
Remove feature flag and delete old form code / REST API code	TBA

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• [-] Code review guidelines
• [-] Merge request performance guidelines
• [-] Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• [-] Label as security and @ mention @gitlab-com/gl-security/appsec
• [-] The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• [-] Security reports checked/validated by a reviewer from the AppSec team

Related to #255603 (closed)