Match OSC reply sequence terminator to OSC request terminator.
Traditionally konsole only was able to parse OSC sequences terminated with non-standard BEL. In 324d78c0 konsole was extended to parse sequences terminated by 7-bit ST (ESC ) as well. But the OSC responses were still hardcoded to reply only with sequences with BEL. But replying to 7-bit ST terminated sequences with a reply terminated by a non-standard terminator is wrong.
This commit passes the terminator along and changes the response to match the original request.
printf "\033]10;?\a"
replies with ^[]10;rgb:fcfc/fcfc/fcfc^G
printf "\033]10;?\033\\"
replies with ^[]10;rgb:fcfc/fcfc/fcfc^[\