fix: update request size calculation to include 2 bytes per item

[timfn-hg]

Description:
This updates the size estimation calculation for pending requests we intend to send to a block node to include an extra 2 bytes of overhead per block item.

Also included are some logging enhancements to aid in debugging sending requests to the block node.

Related issue(s):

Fixes #21923

Notes for reviewer:

Checklist

• Documented (Code comments, README, etc.)
• Tested (unit, integration, etc.)

[lfdt-bot]

✅ Snyk checks have passed. No issues have been found so far.

Status	Scanner	Critical	High	Medium	Low	Total (0)
✅	Open Source Security	0	0	0	0	0 issues

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[alex-kuzmin-hg]

Approved, but I also will add results of SDLT as ultimate evidence of correctness.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 4 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
...app/blocks/impl/streaming/BlockNodeConnection.java	83.33%	0 Missing and 4 partials ⚠️

@@            Coverage Diff            @@
##               main   #21924   +/-   ##
=========================================
  Coverage     70.80%   70.81%           
- Complexity    24387    24388    +1     
=========================================
  Files          2667     2667           
  Lines        104209   104225   +16     
  Branches      10944    10945    +1     
=========================================
+ Hits          73790    73802   +12     
- Misses        26373    26375    +2     
- Partials       4046     4048    +2     

Files with missing lines	Coverage Δ	Complexity Δ
...app/blocks/impl/streaming/BlockNodeConnection.java	90.41% <83.33%> (+0.11%)	80.00 <1.00> (+3.00)

... and 2 files with indirect coverage changes

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[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
✅ +0.00% (target: -1.00%)	✅ 100.00%

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (90ca691)	104114	77791	74.72%
Head commit (1fc9c3d)	104130 (+16)	77805 (+14)	74.72% (+0.00%)

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#21924)	24	24	100.00%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

See your quality gate settings    Change summary preferences

[jsync-swirlds]

Looks good to me.

[timfn-hg]

XTS passing: https://github.com/hiero-ledger/hiero-consensus-node/actions/runs/18953850909 except for an Otter test that is not related and the consensus team is aware of.

[alex-kuzmin-hg]

0 errors, all working OK: https://perf.analytics.eng.hashgraph.io/ephemeral/test_runs/timfn/21923-fix-request-size-calculation_AdHoc7_272/report/longevity/podlog_solo-sdlt-n7/
with this branch ref= 1fc9c3d

[petreze]

Would it make sense