Only actually needed servers should be listed and none is then implied
if no servers are listed.
Outputs a warning if "none" is still set as a server.
Closes#18466
`runtests.pl` defaults to `-` if a command is not set, since
c43ad0f972.
Also:
- drop a stray `</file>`.
- replace a `nothing` with a guaranteed invalid hostname.
Ref: 4334033b43
- replace unused URLs with `-`.
Closes#18319
... as replacements for deprecated CURLOPT_PROTOCOLS and
CURLOPT_REDIR_PROTOCOLS as these new ones do not risk running into the
32 bit limit the old ones are facing.
CURLINFO_PROTCOOL is now deprecated.
The curl tool is updated to use the new options.
Added test 1597 to verify the libcurl protocol parser.
Closes#8992
