When a pull request is created in Bitbucket, you can trigger only chosen jobs for this pull request.
If you want to configure Jenkins to trigger only chosen jobs for pull requests, do the following:
Configure Bitbucket server
Make sure the administrator has added the Jenkins instance credentials to the Webhook's global settings screen. To do so the administrator must go to Administration → Jenkins Servers and add Jenkins instance credentials.
Go to the created pull request and click on the three dots next to the Merge button. Then click Trigger Build:
Now you can choose any instance you have configured and any jobs available for this pull request. After you have selected jobs, press the Trigger button: