iotests/297: Change run_linter() to raise an exception on failure

iotests/297: Change run_linter() to raise an exception on failure

Instead of using a process return code as the python function return
value (or just not returning anything at all), allow run_linter() to
raise an exception instead.

The responsibility for printing output on error shifts from the function
itself to the caller, who will know best how to present/format that
information. (Also, "suppress_output" is now a lot more accurate of a
parameter name.)

Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Hanna Reitz <hreitz@redhat.com>
Message-id: 20211019144918.3159078-9-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>