chore: introduce concurrency env for udf invocation

[yhl25]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 83.33333% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 81.11%. Comparing base (ab8e64c) to head (6f0275f).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
rust/numaflow-core/src/config/monovertex.rs	80.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3317      +/-   ##
==========================================
- Coverage   81.16%   81.11%   -0.05%     
==========================================
  Files         316      317       +1     
  Lines       72828    72911      +83     
==========================================
+ Hits        59108    59139      +31     
- Misses      13163    13218      +55     
+ Partials      557      554       -3     

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