[7.2.1] Fix MXR writes

[causten]

Motivation

Fix underflow bug with msgpack_size_limit chunking logic. The underflow makes it appear we had more data than necessary to pack causing EOF and other sorts of packing issues

Technical Details

Merge PR#4480 in to the 7.2 branch

Changelog Category

• • Added: New functionality.
• • Changed: Changes to existing functionality.
• • Removed: Functionality or support that has been removed. (Compared to a previous release)
• • Optimized: Component performance that has been optimized or improved.
• • Resolved Issues: Known issues from a previous version that have been resolved.
• • Not Applicable: This PR is not to be included in the changelog.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

Additional details and impacted files

@@                  Coverage Diff                  @@
##           release/rocm-rel-7.2    #4494   +/-   ##
=====================================================
  Coverage                 92.21%   92.21%           
=====================================================
  Files                       561      561           
  Lines                     27228    27228           
=====================================================
  Hits                      25107    25107           
  Misses                     2121     2121           

Files with missing lines	Coverage Δ
src/msgpack.cpp	85.42% <100.00%> (ø)

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