Alerts Service only available at the project-level

What does this MR do?

A smallish MVC to handle both:

• #273168 (closed)

The initial issue was the Alert integration service throwing a 500 error on the group or admin section, however unpon clarification it seems we should only offer Alerts on a project level via: Operations > Alerts

See: !48293 (comment 453988329)

Given that, this merge removes access to this old section from these areas:

• Group
• Admin

Alert Service should not be available for either a group or admin section, only on a project level.

Screenshots (strongly suggested)

Project	Group	Admin

In the following milestone we will depreciate it from projects.

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 #273168 (closed), #292396 (closed)