The file-test pod still hangs sometimes when exiting. Instead of
trapping SIGTERM as before, use tini's `-g` option to kill the process
group. According to further reading on bash signal handling [1], Ctrl-C
sends a kill signal to the entire process group in order to kill `sleep`
commands.
[1] Link also noted in code comments:
http://mywiki.wooledge.org/SignalTrap#When_is_the_signal_handled.3F
Signed-off-by: Blaine Gardner <blaine.gardner@suse.com>