fix: close tmp fs and evict udf modules on ExecutorManager.close()

[Ma77Ball]

What changes were proposed in this PR?

The executor_manager fixture in test_executor_manager.py guarded its cleanup with hasattr(manager, "_fs"), but the @cached_property attribute is named fs, so the guard was always false and manager.close() never ran. This leaked TempFS directories into /var/tmp on every test run. Even when close() did run from the sibling fixture, it only closed the filesystem and left stale udf-vN entries in sys.modules plus the tmp directory in sys.path. This PR drops the broken guard and extends ExecutorManager.close() to also remove the module from sys.modules and the path from sys.path, so a single close() call fully reverses every global side effect of fs and load_executor_definition.

Any related issues, documentation, or discussions?

Closes: #4730

How was this PR tested?

• All 20 tests in test_executor_manager.py pass.
• Verified /var/tmp no longer accumulates TempFS directories after a test run.
• Verified no leaked udf-v* files anywhere under /tmp or /var/tmp after a run.

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

Co-authored with Claude Opus 4.7 in compliance with ASF

[Ma77Ball]

@chenlica please assign a reviewer.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 43.37%. Comparing base (bb795a0) to head (94770c6).

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #5046      +/-   ##
============================================
+ Coverage     42.81%   43.37%   +0.55%     
+ Complexity     2206     2172      -34     
============================================
  Files          1045     1035      -10     
  Lines         40119    38750    -1369     
  Branches       4239     4051     -188     
============================================
- Hits          17178    16806     -372     
+ Misses        21875    20892     -983     
+ Partials       1066     1052      -14     

Flag	Coverage Δ		*Carryforward flag
access-control-service	39.53% <ø> (ø)		Carriedforward from c93c8f7
agent-service	33.72% <ø> (ø)		Carriedforward from c93c8f7
amber	43.17% <ø> (-0.52%)	⬇️	Carriedforward from c93c8f7
computing-unit-managing-service	0.00% <ø> (ø)		Carriedforward from c93c8f7
config-service	0.00% <ø> (ø)		Carriedforward from c93c8f7
file-service	32.10% <ø> (-0.09%)	⬇️	Carriedforward from c93c8f7
frontend	35.17% <ø> (+1.24%)	⬆️	Carriedforward from c93c8f7
python	88.94% <100.00%> (-0.03%)	⬇️
workflow-compiling-service	47.72% <ø> (ø)		Carriedforward from c93c8f7

*This pull request uses carry forward flags. Click here to find out more.

☔ 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.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[chenlica]

@mengw15 @bobbai00 Please review it.

[Yicong-Huang]

Also please make coverage happy ;) thanks

[Yicong-Huang]

LGTM