[api-baggage] revert space encoding change

[lachmatt]

Changes

Revert changes from #5303 because Uri.UnescapeDataString doesn't replace percent-encoded octet sequences that do not match the UTF-8 encoding scheme with the replacement code point (U+FFFD). This is required by the W3C Baggage spec.

The plan is to address all of the issues related to baggage propagation with the later release.

Merge requirement checklist

• CONTRIBUTING guidelines followed (license requirements, nullable enabled, static analysis, etc.)
• Unit tests added/updated
• Appropriate CHANGELOG.md files updated for non-trivial changes
• Changes in public API reviewed (if applicable)

[vishweshbankwar]

Add this PR # as well.

[lachmatt]

Added in e474fa7

[alanwest]

Please add more information about why we're reverting this change to the changelog or PR description. Something to the effect of "... because the fix did not properly address the inconsistency with the baggage spec. We will address this issue more completely in a later release"

[lachmatt]

PR description updated.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.99%. Comparing base (6250307) to head (a0d4af5).
Report is 258 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5687      +/-   ##
==========================================
+ Coverage   83.38%   85.99%   +2.61%     
==========================================
  Files         297      254      -43     
  Lines       12531    11054    -1477     
==========================================
- Hits        10449     9506     -943     
+ Misses       2082     1548     -534     

Flag	Coverage Δ
unittests	?
unittests-Project-Experimental	85.94% <100.00%> (?)
unittests-Project-Stable	85.99% <100.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

Files	Coverage Δ
...metry.Api/Context/Propagation/BaggagePropagator.cs	85.48% <100.00%> (ø)

... and 124 files with indirect coverage changes

[alanwest]

When we circle back to fixing this again, we should start with a solid test suite and vet it across other language implementations. Without a well-vetted test suite it is difficult to review and be confident in these fixes because most people do not have the depth of familiarity required of the baggage specification.