- when server are killed by a test case, do not wait for the server lock
file to go away. These tests are mostly about client timeouts and the
server will hang until killed.
- when killing a server successfully, check for a remaining lock file,
log its existence and remove it.
- lower the delay timings on SLOWDOWN by half
- add SLOWDOWNDATA server command to only slow down the FTP data bytes,
not the control ones.
- lower some timeout values
Closes#14835
