NIFI-16339 Stabilize race conditions in scheduler and Python NAR reupload tests

[abij]

Summary

NIFI-16339

Two unit/system tests contain timing-sensitive race conditions that intermittently fail CI on unrelated pull requests, forcing maintainers to re-run jobs. This PR makes both tests tolerant of valid asynchronous state transitions without changing any production behavior.

TestStandardProcessScheduler.validateNeverEnablingServiceCanStillBeDisabled

disableControllerService(...) is asynchronous. When disabling a controller service whose @OnEnabled is still blocked, the node may already have reached DISABLED by the time the test inspects the state, rather than being observed in the intermediate DISABLING state. Both are valid outcomes, so the strict equality assertion is timing-dependent and fails on fast/loaded runners (observed on Windows Zulu JDK 21):

TestStandardProcessScheduler.validateNeverEnablingServiceCanStillBeDisabled:508
expected: <DISABLING> but was: <DISABLED>

The assertion now accepts either DISABLING or DISABLED.

PythonNarDeletionDuringInitIT.testNarReuploadAfterForceDeleteDuringInit

After a re-uploaded NAR reaches INSTALLED, processor-type discovery can lag briefly, so a single immediate lookup can return null and fail assertNotNull. The test now polls for the processor type (200 ms interval, 30 s monotonic deadline) before asserting.

Out of scope

Several clustered/system tests intermittently hit their 5-minute @Timeout during node startup on CI (worst on ubuntu-24.04 Java 25). The failing test rotates run-to-run (e.g. AutoResumeStateClusteredIT, OffloadContentClaimTruncationIT, FlowSynchronizationIT, ClusteredConnectorTroubleshootingIT, ControllerServiceStateIT). Because there is no single root cause in test logic (only shared timeout pressure), these are tracked separately as CI/runner performance flakiness and are not addressed here.

Tracking

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Build

• Build completed using ./mvnw clean install -P contrib-check
  • JDK 21
  • JDK 25

Licensing

• New dependencies are compatible with the Apache License 2.0 according to the License Policy — no new dependencies

Documentation

• Documentation not required — test-only change