fix(blockbuilder): copy entries returned by record decoder

[ashwanthgoli]

What this PR does / why we need it:
Record decoder reuses the stream and entries slice, this would not be a problem if these entries are consumed synchronously. But the block builder buffers the entries and consumes them in batches through a channel while the decoder reuses the entries slice on each decode call.
Making a copy of the entries to avoid this problem.

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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[owen-d]

nice catch!