#234: Do not require a workspace to notify Bitbucket

[nathanhi]

Implements #234

Historically, the stashNotifier plugin required a workspace context in order to perform the plugin task, albeit not making use of the workspace in any way.

This change removes the implementation of the perform method requiring a workspace and replaces it with the one not requiring a workspace.

Testing done

Regular pipeline (without workspace)

Created a simple Pipeline checking out a Git repository on a specific node with the pipeline not requiring one; notifications work as intended:

pipeline {
    agent none

    stages {
        stage('Hello') {
            agent {
                label 'linux'
            }

            steps {
                git branch: 'foo', changelog: false, credentialsId: '****', poll: false, url: '****/jenkins_bitbucket_notifier.git'
                echo 'Hello World'
            }
        }
    }

    post {
        always {
            notifyBitbucket()
        }
    }
}

Regular pipeline (with workspace)

Created a simple Pipeline that allocates a node top-level; notifications work as intended/before:

pipeline {
    agent {
        label 'linux'
    }

    stages {
        stage('Hello') {
            steps {
                git branch: 'foo', changelog: false, credentialsId: '****', poll: false, url: '****/jenkins_bitbucket_notifier.git'
                echo 'Hello World'
            }
        }
    }

    post {
        always {
            notifyBitbucket()
        }
    }
}

Regular pipeline (with node(null) in post)

pipeline {
    agent none

    stages {
        stage('Hello') {
            agent {
                label 'linux'
            }

            steps {
                git branch: 'foo', changelog: false, credentialsId: '****', poll: false, url: '****/jenkins_bitbucket_notifier.git'
                echo 'Hello World'
            }
        }
    }

    post {
        always {
            script {
                node(null) {
                    notifyBitbucket()
                }
            }
        }
    }
}

Freestyle job

Triggered a freestyle build with a post-build action to notify Bitbucket -> still works as intended (pre- and post-build notifications are sent).

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
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• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue