Remove the old tekton version

[juliusvonkohout]

Validation Checklist

• [X] Is this a Kubeflow issue?
• [X] Are you posting in the right repository ?
• [X] Did you follow the installation guide https://github.com/kubeflow/manifests?tab=readme-ov-file ?
• [X] Is the issue report properly structured and detailed with version numbers?
• [X] Is this for Kubeflow development ?
• [X] Would you like to work on this issue?
• [X] You can join the CNCF Slack and access our meetings at the Kubeflow Community website. Our channel on the CNCF Slack is here #kubeflow-platform.

Version

master

Describe your issue

Check from the main readme Kubeflow Tekton Pipelines apps/kfp-tekton/upstream [2.0.5](https://github.com/kubeflow/kfp-tekton/tree/2.0.5

and the folder /https://github.com/kubeflow/manifests/tree/master/apps/kfp-tekton/upstream

both must be deleted since they have been merged into KFP.

@rimolive

We should also delete https://github.com/kubeflow/manifests/blob/master/.github/issue_label_bot.yaml