fix: Processor now gets passed in reference #2726

[Puffy1215]

Fixes #2726

Changes

See #2726. Previous implementation was not up to spec. I replaced the on_end() trait function parameter with a &mut reference to SpanData, and refactored from there. Cloning still happens inside BatchSpanProcessor where necessary. If there are any unnecessary clones that are still happening that I can fix, please let me know.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[linux-foundation-easycla]

The committers listed above are authorized under a signed CLA.

• ✅ login: Puffy1215 / name: Andy (b7efe12, 7d82c3e, b461111, 09989bb, 3684483, 9b1c9d7, f4a2080, 4df8134)
• ✅ login: lalitb / name: Lalit Kumar Bhasin (6f81a7d)

[codecov]

Codecov Report

Attention: Patch coverage is 98.21429% with 1 line in your changes missing coverage. Please review.

Project coverage is 81.3%. Comparing base (10cf02c) to head (4df8134).

Files with missing lines	Patch %	Lines
opentelemetry-sdk/src/trace/span.rs	93.7%	1 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2895   +/-   ##
=====================================
  Coverage   81.3%   81.3%           
=====================================
  Files        126     126           
  Lines      24254   24259    +5     
=====================================
+ Hits       19736   19745    +9     
+ Misses      4518    4514    -4     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[cijothomas]

@Puffy1215 Could you clear the EasyCLA check? The bot comment should have all instructions. You'd probably want to consult your employer if contributing on behalf. (This is a one time requirement, before we can accept contributions)
Thank you!