refactor(alpha): adjust resources for core sts

[aabouzaid]

Which problem does the PR fix?

Fixes: #2583

What's in this PR?

Adjust resources (requests and limits) for Core StatefulSet, which now includes Operate, Tasklist, and later Optimize.

The Zeebe team will make another benchmark after alpha 3 and could adjust it again if needed.

Checklist

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