ECE: Disabling CPU hard limit and podman limitation

[eedugon]

This PR introduces the CPU hard limit configuration (enable / disable) within the Resource overrides page, and it describes that it doesn't have any effect on Podman hosts.

I have also refined the introduction of the page.

Preview:

• Resource Overrides

The reason of adding this is:

• This is available in ECE UI for all users and we didn't have it documented anywhere (thanks @frconil for pointing this out). So there's no point of hiding this button of the UI.
• We have some public KB articles that also mention this setting (CPU hard limit toggling).
• We now want to introduce a banner saying that this doesn't work in Podman, but we didn't have this even documented at all.

I have added some warnings and implications of using this setting, and recommending to do it only when being guided by Support.

This PR will also be aligned with #1418 for the Podman limitation.

[shainaraskas]

tiny suggestions for you, otherwise good. assume we have validated that this is safe to share

[shainaraskas]

tiny suggestions for you, otherwise good. assume we have validated that this is safe to share

[brendandw]

This looks good to me

[matt-elastic]

LGTM!

[github-actions]

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