Reduce contribution of RLE blocks size in page splitting

[raunaqmorarka]

Description

Consider only the underlying value block size for RLE blocks in page splitting calculation.
This prevents the splitting up of Pages due to getSizeInBytes of RLE blocks being a factor of positions count

Additional context and related issues

Follow-up of #25256 (comment)

Release notes

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## Section
* Fix some things. ({issue}`issuenumber`)

[starburstdata-automation]

Started benchmark workflow for this PR with test type = iceberg/sf1000_parquet_part.

Building Trino finished with status: success
Benchmark finished with status: success
Comparing results to the static baseline values, follow above workflow link for more details/logs.
Status message: NO Regression found.
Benchmark Comparison to the closest run from Master: Report

[starburstdata-automation]

Started benchmark workflow for this PR with test type = iceberg/sf1000_parquet_unpart.

Building Trino finished with status: success
Benchmark finished with status: success
Comparing results to the static baseline values, follow above workflow link for more details/logs.
Status message: NO Regression found.
Benchmark Comparison to the closest run from Master: Report

[raunaqmorarka]