untouched UI toggles do not create values in the config

[sherifnada]

Expected Behavior

when I setup the salesforce source, I don't expect to need to toggle is_sandbox to true then false for its value to be false in the config sent to the backend.

Actual behavior

if I don't touch the toggle, the config generated from the UI to the backend does not contain the is_sandbox field, which causes validation on the backend to fail. I have to flick it to true then false.

[sherifnada]

Fixed