Added SemaphoreStep.waitForStart() for workflow to wait until semaphore release before continuing.

[cdgopal]

Added SemaphoreStep.waitForStart() for workflow to wait until semaphore release before continuing.

Description and fix: Previously, reliance on specific console messages for synchronization could lead to inconsistency and intermittent failures. By shifting to semaphore-based synchronization, the workflow ensures stability and predictability in execution.

Transitioning to SemaphoreStep.waitForStart() provides a more reliable synchronization approach, reducing flakiness risk linked to console message dependency.

Following is the error:

Testing done

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[jglick]

@cdgopal this looks right to me and seems to complement jenkinsci/workflow-support-plugin#258; why was it closed?

[cdgopal]

@cdgopal this looks right to me and seems to complement jenkinsci/workflow-support-plugin#258; why was it closed?

@jglick This is public repo. As Raul suggested to create OSS ticket in jenkins Jira Jenkins - Jenkins Jira
for the affected plugin for the public repo but I am not familiar to create OSS ticket i.e. I closed this PR. Please suggest.

[cdgopal]

@jglick Please consider this PR "#531"