This is the %CLIENT6IP variable - but without outmost brackets since
some commmand lines need the address without the brackets. With this
variable we can run three more tests without prechecks.
Closes#15039
Some feature names used in tests had minor differences compared to
the well-known ones from `curl -V`. This patch syncs them to make test
results easier to grok.
Closes#14183
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
