Remove influxdb entry points

What does this MR do?

Note: This MR is currently set to merge into !30786 (merged). Once that MR is merged, this will be pointed to master. This is now pointed at master.

This MR is part of deprecating influxdb. The full process is #122311 (comment 336258151)

This removes most of the implementation details of influxdb.

Screenshots

Prometheus graphs

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry not user-facing and !30786 (merged) had an 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