drm/i915/guc: Enable CT_DEAD output in regular debug builds

There is a sporadic failure to enable CTs ocurring in CI on one
specific machine that can't be reproduced locally. The driver already
supports dumping out a whole bunch of GuC related debug info on such a
failure but only when the verbose GuC debug config option is enabled.
It would be preferable to not enable all the verbose debug output. So
just bump the CT_DEAD code to regular I915 debug level rather than GUC
debug level, at least temporarily for CI.

To prevent excessive spam in other parts of CI, also add a check
against doing a CT_DEAD dump during an error injection test. No point
in dumping large amounts of 'why did this fail' info when the fail is
deliberately induced.

v2: Revert accidentally enabling some other verbose debug output.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://lore.kernel.org/r/20250614030222.105601-1-John.C.Harrison@Intel.com