Move test-runner.1 into top-level man/

dist delta:

+zfs-2.1.99/man/man1/test-runner.1
-zfs-2.1.99/tests/test-runner/man/
-zfs-2.1.99/tests/test-runner/man/test-runner.1

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13316