[SEMANTIC CONVENTIONS] Upgrade to version 1.26.0

[lalitb]

Changes

• Upgraded to semantic conventions release v1.26.0.
• Implemented a workaround for rust name collision:
  - Deprecated messaging.client_id is now generated as MESSAGING_CLIENT_ID.
  - messaging.client.id is also generated as MESSAGING_CLIENT_ID.
  - Removed code generation for messaging.client_id.
  - See related issue: messaging.client_id -> messaging.client.id rename causes issues with code generation semantic-conventions#1031, and the similar changes are done for otel-cpp.

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)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.4%. Comparing base (82fa485) to head (88e12ab).

Additional details and impacted files

@@           Coverage Diff           @@
##            main   #1851     +/-   ##
=======================================
- Coverage   74.5%   74.4%   -0.1%     
=======================================
  Files        122     122             
  Lines      19800   19800             
=======================================
- Hits       14752   14747      -5     
- Misses      5048    5053      +5     

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[cijothomas]

LGTM
We may want to consider moving this to contrib repo in the future.