Remove --additional-height logic from graph when in the left position

[das7pad]

Fixes #928

This PR is a potential fix for #928.

I noticed this expensive "scroll" handler and in testing the implications of removing it, it seemed that this is actually fixing a bug. The extra offset may have been required in the past.

Testing done

pipeline {
    agent any

    stages {
        stage('Hello') {
            steps {
                script {
                    for(int i=1; i<=3; i++) {
                        stage("Stage - ${i}") {
                            sh 'for i in `seq 13`; do sleep 0.5; echo "Slept ${i} times"; done'
                        }
                    }
                }
            }
        }
    }
}

• select "left" position for graph
• scroll to the bottom

before	after

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
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests that demonstrate the feature works or the issue is fixed

[timja]

Seems fine, tested and could reproduce the issue before and not after

I'll ship it, but @janfaracik you remember if this is needed for anything?