[DOCS] Enhance troubleshooting high cpu page. Opster migration

[thekofimensah]

This is importing additional information given in the Opster docs for high cpu issues.

Summary of changes:

1. Moved the “Hotspotting” paragraph at the beginning into the “Tips and Solutions” section for better contextual fit, incorporating extra details from the Opster documentation.
2. Added new subsections to “Tips and Solutions,” specifically covering JVM garbage collection and oversharding.
3. Separated the previous three points (“Scale your cluster,” “Spread out bulk requests,” and “Cancel long-running searches”) into a distinct section, as they are less common scenarios and more general best practices rather than direct solutions to typical high CPU issues.

This is the backport: elastic/elasticsearch#125558

[thekofimensah]

@leemthompo I'm still getting this issue where the md redirect goes to the middle of the page. I think wherever the link is in the original page, it is automatically scrolled to that same place in the new page.

It would be great if you can check the "hot spotting" or "data tier" link and if it's not just me, I can create a ticket

[thekofimensah]

@georgewallace

[shainaraskas]

I think this is ok to go now, but I provided a couple of suggestions we could address while we're here

[github-actions]

🔍 Preview links for changed docs

• troubleshoot/elasticsearch/high-cpu-usage.md