ktest.pl: Remove unused declarations in run_bisect_test function

ktest.pl: Remove unused declarations in run_bisect_test function

[ Upstream commit 776735b954f49f85fd19e1198efa421fae2ad77c ]

Since $output and $ret are not used in the subsequent code, the declarations
should be removed.

Fixes: a75fececff3c ("ktest: Added sample.conf, new %default option format")
Link: https://lore.kernel.org/20240902130735.6034-1-bajing@cmss.chinamobile.com
Signed-off-by: Ba Jing <bajing@cmss.chinamobile.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>