This now insists on using a server auth option unless --insecure is
provided. As an added bonus, it now also only checks for the knownhosts
file once (if found).
Ref: #16197Closes#16205
The threee tags `<name>`, `</name>` and `<command>` were frequently used
with a leading space that this removes. The reason this habbit is so
widespread in testcases is probably that they have been copy and pasted.
Hence, fixing them all now might curb this practice from now on.
Closes#12028