Preserve Trigger Rules and Variables When Changing Incident Source

When a user changes the source associated with a trigger rule under Incoming Incident configuration, all previously defined rules and customer variables are deleted rather than preserved. This enhancement would allow the source to be changed without removing existing trigger rules and variables, or would prompt users with a clear warning and option to retain or migrate the configuration before any deletion occurs. Preserving this configuration would prevent unintended data loss and reduce the effort required to reconfigure complex trigger setups after a source change.