[DSG] Edit data connection from workbench Edit page does not switch properly

Description of problem:

By creating a DC from workbench creation/edit page we can connect more than one DC to a single workbench. In the past we have limited the number of possible DC connection to 1 for each workbench in RHODS-5701 . 

Even if a workbench gets connected to multiple DC, they can access only the second one, as already known in RHODS-5701.

Prerequisites (if any, like setup, operators/versions):

Steps to Reproduce

1. create a workbench and create a DC directly from the creation page
2. go to Edit page of the workbench and switch from "use existing data connection" to "create new data connection"
3. insert data of the new DC
4. click "Update workbench" button
5. check in the DS Project details page that the workbench is connected to multiple DCs

Actual results:

multiple data connections remain connected to the same workbench

Expected results:

previous data connection gets disconnected from the workbench, while the new one gets connected to it

Reproducibility (Always/Intermittent/Only Once):

Always

Build Details:

RHODS v1.25

Workaround:

Manually disconnect the previous data connection from the workbench

Additional info: