Ohara: Remove "workerClusterName" from Pipeline

[chia7712]

We are be cognizant of the fact that too strict checks for Pipeline APIs is unnecessary and depart from decoupling APIs and UI flow. #1655 got rid of too strict checks for Pipeline APIs. On account of APIs compatibility, "workerClusterName" is useless but it still lie in Pipeline.

• [x] Remove "workerClusterName" from Pipeline with manager #2186

[chia7712]

@wu87988622 @konekoya Could we resolve this one in 0.7?

[wu87988622]

@wu87988622 @konekoya Could we resolve this one in 0.7?

This issues will finish in 0.7.

[chia7712]

@wu87988622 please add the link to PR for sub task.