test: improper teardown in jest

[ANGkeith]

When the handler throws error in the test suites, cleanupJobResources is not called, resulting in dangling resources. This should fix the openHandle warning when running the tests

• initially had another idea which is to wrap the handler with a try/finally block to https://github.com/firecow/gitlab-ci-local/blob/master/src/handler.ts#L24, but it's messy since we're catching the errors in src/index.ts so for now went with this, which should be less disruptive

[sonarcloud[bot]]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

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