[Backport 0.24] Fix flaky CancelWorkflowInstanceConcurrentlyTest

[korthout]

Description

There was a timing issue in the multi-instance scenario, where the test
did not wait for both of the jobs to be created. Then when re-starting
the engine, reprocessing occurs including the verification of
reprocessing which would then fail because of this inconsistency.

By waiting for 2 jobs to be created and then taking the 1 of the correct
type, instead of just waiting for the 1 job, the test has become stable..

Related issues

closes #3606

Definition of Done

Not all items need to be done depending on the issue and the pull request.

Code changes:

• The changes are backwards compatibility with previous versions
• If it fixes a bug then PRs are created to backport the fix to the last two minor versions

Testing:

• There are unit/integration tests that verify all acceptance criterias of the issue
• New tests are written to ensure backwards compatibility with further versions
• The behavior is tested manually
• The impact of the changes is verified by a benchmark

Documentation:

• The documentation is updated (e.g. BPMN reference, configuration, examples, get-started guides, etc.)
• New content is added to the release announcement

[Zelldon]

bors r+

[zeebe-bors]

Build succeeded:

• continuous-integration/jenkins/branch