Add support for other stackprof profiles

What does this MR do?

We've had support for creating stackprof profiles for a while now. However, the current implementation is limited to creating CPU profiles. This change adds support for other profile modes such as object.

This is controlled throgh a new env var STACKPROF_MODE.

Since object allocations are not sampled based on frequency but based on allocation events, I decided to rename the interval env var to just STACKPROF_INTERVAL since it is not always provided in microseconds i.e. time units anymore.

I also streamlined logging a bit by pulling it out into a helper and by prefixing all labels with profile_ so as not to pollute the global Kibana label namespace with this.

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
• Tested manually -- this is difficult to unit test.