tests: fix the bug of sentinel.conf

Even CONFIG_HW_STACK_PROTECTION is no here,
it is still yes as it will be re-selected by
CONFIG_TEST_HW_STACK_PROTECTION in tests/Kconfig.

So the correct setting here is:

CONFIG_TEST_HW_STACK_PROTECTION=n

This fixes #8092 (case1)

Signed-off-by: Wayne Ren <wei.ren@synopsys.com>