fix: Revert "perf: Fix memory leak in cachedIterator (#17628)" (backport k264)

[loki-gh-app]

Backport 0316740 from #18687

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This reverts commit 87aa954.

What this PR does / why we need it:

Reverts #17628 as it seems to be affecting the correctness of forward queries. The exact problem is not well understood yet, but we suspect that we are closing wrapped iterator before consuming all of the required entires

Which issue(s) this PR fixes:
Fixes #

Special notes for your reviewer:

Checklist

• Reviewed the CONTRIBUTING.md guide (required)
• Documentation added
• Tests updated
• Title matches the required conventional commits format, see here
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[ashwanthgoli]

lgtm