WIP: Call `GC::Profiler.clear` only in one place

What does this MR do?

Previously, both InfluxSampler and RubySampler were relying on the GC::Profiler.total_time data which is the sum over the list of captured GC events.

Also, both samplers asynchronously called GC::Profiler.clear which led to incorrect metric data because each sampler had the wrong assumption it was the only object who called GC::Profiler.clear and thus could rely on the gathered results between calls.

We should ensure that GC::Profiler.total_time is called only in one place making it possible to rely on accumulated data between profiler wipes.

Note: InfluxDB is considered deprecated, so we only need to support Prometheus metrics.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry for user-facing changes, or community contribution. Check the link for other scenarios.
• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Performance 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

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 #63571 (closed)