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
... and use this new keywords in all the test files larger than 50K to reduce
their sizes and make them a lot easier to read and understand.
Closes#6040
