fix: change block per-item byte overhead from 2 bytes to 5 bytes for requests

[timfn-hg]

Description:
This updates the number of bytes we add for each block item for potential overhead from 2 bytes to 5 bytes.

During recent performance testing, there were several cases where requests would be created with a serialized size larger than we expected. As we build a "pending request" we make an effort to estimate what the size of the request would be by taking a baseline of 100 bytes and then adding for each item, the BlockItem#protobufSize with 2 extra bytes. However, these two bytes seem to small, so we will update it to 5 bytes each which should cover most, if not all, cases. While each item may not have 5 bytes of overhead in reality, by adding this to each item we hopefully avoid cases where we aren't assigning enough overhead.

Related issue(s):

This PR is a followup to a previous PR that tried to address ticket #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.

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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 (c0f3f9b)	104313	78030	74.80%
Head commit (51a91e1)	104313 (+0)	78030 (+0)	74.80% (+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 (#22019)	1	1	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%

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

@@            Coverage Diff            @@
##               main   #22019   +/-   ##
=========================================
  Coverage     70.90%   70.90%           
  Complexity    24430    24430           
=========================================
  Files          2668     2668           
  Lines        104408   104408           
  Branches      10965    10965           
=========================================
  Hits          74030    74030           
  Misses        26333    26333           
  Partials       4045     4045           

Files with missing lines	Coverage Δ	Complexity Δ
...app/blocks/impl/streaming/BlockNodeConnection.java	90.35% <100.00%> (ø)	83.00 <0.00> (ø)

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