Metrics index from annotations

[sbylica-splunk]

Description:
Added support for annotations in metrics index

Testing:
Unit test

Documentation:
Added short explanation to advanced-configuration.md

[rmfitzpatrick]

@sbylica-splunk why is a new k8sattributes processor being added for all components instead of enhancing the existing agent's? I don't believe these attrs are necessary for o11y cloud cases so limiting to platform w/ metrics configurations seems preferable as well.

[atoulme]

Please rebase and rerun make render

[sbylica-splunk]

Please rebase and rerun make render

Done

[sbylica-splunk]

o11y cloud cases

I added a new processor because we already have similar use case for logs (k8sattributes processor) and I wanted to make sure it works the same way.
As for you second question, do you mean something like that?

  {{- if (eq (include "splunk-otel-collector.platformMetricsEnabled" $) "true") }}
  -  k8sattributes/metrics
  {{- end }}

[rmfitzpatrick]

As for you second question, do you mean something like that?

Yes, though I think we'll also want to ensure that the new attributes aren't exported as o11y metric dimensions via the signalfx exporter. I'm not sure if there's a way to do that other than duplicating pipelines or using a connector w/ an additional transform processor. Maybe @dmitryax has suggestions since I think he's better versed on the use case than I am.

[dmitryax]

@sbylica-splunk please make it conditional. At least if splunk-otel-collector.platformMetricsEnabled as @rmfitzpatrick suggested. Also, keep in mind that it introduces a significant memory utilization overhead

[sbylica-splunk]

Ok, so is there anything else to do? I'll squash current commits after this pr is good to go :)

[jinja2]

@sbylica-splunk please fix trailing whitespace issues as seen in the failing pre-commit job