tracing/selftests: Run the ownership test twice

A regression happened where running the ownership test passes on the first
iteration but fails running it a second time. This was caught and fixed,
but a later change brought it back. The regression was missed because the
automated tests only run the tests once per boot.

Change the ownership test to iterate through the tests twice, as this will
catch the regression with a single run.

Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>