fix(pyamber): make ExecutorManager module names process-globally unique

[Yicong-Huang]

What changes were proposed in this PR?

Lift ExecutorManager's tmp module-name counter from a per-instance attribute to a process-wide itertools.count(1). Generated module names (udf-vN) are now unique across every instance in the same Python process, so the if module_name in sys.modules: clear()+reload() recovery branch (which silently returned a stale class on 3.11) is unreachable and removed.

Production path is unchanged — a worker process holds exactly one ExecutorManager and its counter was already monotonic across reconfigures.

Any related issues, documentation, discussions?

Closes #4705.

How was this PR tested?

sbt 'WorkflowExecutionService / Test / testOnly test_executor_manager test_main_loop' — 23/23 pass. The combined run that previously leaked TestOperator from test_executor_manager.py into test_main_loop.py's fixtures is now clean.

test_executor_manager.py updated for the new semantics: assertions on executor_version == 0/1 and operator_module_name == "udf-v1" change to relative-ordering checks since the counter's absolute starting value depends on prior tests in the session.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Opus 4.7, 1M context)

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.66%. Comparing base (e551e1b) to head (3d2af92).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #4717      +/-   ##
============================================
- Coverage     43.68%   43.66%   -0.02%     
+ Complexity     2087     2086       -1     
============================================
  Files           957      957              
  Lines         34077    34072       -5     
  Branches       3753     3753              
============================================
- Hits          14887    14879       -8     
- Misses        18395    18397       +2     
- Partials        795      796       +1     

Flag	Coverage Δ
amber	41.96% <ø> (-0.02%)	⬇️
python	86.46% <100.00%> (-0.02%)	⬇️

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[Copilot]

Pull request overview

This PR fixes cross-test contamination in PyAmber by making ExecutorManager’s temporary module names process-globally unique, preventing sys.modules name collisions that could cause stale operator classes to be reused (notably on Python 3.11).

Changes:

• Replace per-ExecutorManager module-name/version counter with a class-level itertools.count(1) counter.
• Remove the sys.modules “module already loaded” clear+reload branch since module-name collisions should no longer occur.
• Update test_executor_manager.py assertions to validate module-name shape and monotonic ordering rather than fixed udf-v1 / version values.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
amber/src/main/python/core/architecture/managers/executor_manager.py	Makes tmp module names process-unique via a class-level counter and simplifies import logic by removing the reload path.
amber/src/main/python/core/architecture/managers/test_executor_manager.py	Adjusts tests to match process-wide counter semantics and checks monotonic module naming.

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