fix: test cleanup

[aaron-steinfeld]

Description

Fixed a few issues that came up when debugging an integration test shutdown. Shutdown was called an excessive number of times:

1. We called IntegrationTestServiceLauncher.shutdown() for every running service, but shutdown() already loops through all services.
2. We had a shutdown hook that ran on thread close, but the tests are manually shutdown (and thread is shared across tests so doesn't match the test's lifecycle
3. We used a static PLATFORM_SERVICES variable to track started services, then shutdown loops through each and shuts them down. This static was never cleared, so the same services were accumulating across tests.

[github-actions]

Test Results

31 tests  ±0   31 ✔️ ±0   11s ⏱️ ±0s
  9 suites ±0     0 💤 ±0 
  9 files   ±0     0 ❌ ±0 

Results for commit 97d62e0. ± Comparison against base commit d518316.

♻️ This comment has been updated with latest results.

[codecov]

Codecov Report

Merging #72 (97d62e0) into main (d518316) will not change coverage.
The diff coverage is n/a.

@@            Coverage Diff            @@
##               main      #72   +/-   ##
=========================================
  Coverage     70.57%   70.57%           
  Complexity      106      106           
=========================================
  Files            15       15           
  Lines           588      588           
  Branches         32       32           
=========================================
  Hits            415      415           
  Misses          154      154           
  Partials         19       19           

Flag	Coverage Δ
unit	70.57% <ø> (ø)

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[aaron-steinfeld]

We'll need to be careful with this one. It introduces a subtle issue that requires a gradle version upgrade.