Remove the Activity option in the operation drop-down list of the pipeline list page.

Created by: patrickluoyu

Describe the bug

The Activity option as shown in the following figure is redundant and should be removed, because its only function is to go the Activity tab of the pipeline details page.

Versions used(KubeSphere/Kubernetes) KubeSphere: 3.2 alpha 1

Expected behavior

/assign @harrisonliu5 @LinuxSuRen