test: add cpuprofile arg support to benchmark make task

[kruskall]

Motivation/summary

Add BENCHMARK_CPU_OUT variable and pass cpuprofile arg to apmbench.

This PR allows creating cpu profile when running benchmark to investigate performance issues.

Checklist

• Update CHANGELOG.asciidoc
• Update package changelog.yml (only if changes to apmpackage have been made)
• Documentation has been updated

For functional changes, consider:

• Is it observable through the addition of either logging or metrics?
• Is its use being published in telemetry to enable product improvement?
• Have system tests been added to avoid regression?

How to test these changes

1. BENCHMARK_CPU_OUT=cpu.out make run-benchmark
2. BENCHMARK_CPU_OUT=cpu.out make cp-cpuprof
3. open cpu.out file locally

Related issues

[mergify]

This pull request does not have a backport label. Could you fix it @kruskall? 🙏
To fixup this pull request, you need to add the backport labels for the needed
branches, such as:

• backport-7.17 is the label to automatically backport to the 7.17 branch.
• backport-8./d is the label to automatically backport to the 8./d branch. /d is the digit.

NOTE: backport-skip has been added to this pull request.

[v1v]

run docs-build