Store: read uint32 while checking snapshot import consistency

This is a followup MR of !12262 (merged).

The offsets of the cemented files are encoded as signed int32 but were decoded as signed int31 while checking the consistency of the cemented stores while importing a snapshot. This was issue when checking cycles containing many big blocks (> ~1Gb cycles).

We now switch to uint32.

Closes: #7144 (closed)

Manually testing the MR

Import a recent ghostnet full snapshot (containing cycle 960, i.e after 15 March 2024) and encounter the error describe in #7144 (closed).

Check that it works with the fix.

Checklist

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