drm/xe/guc: Add firmware build type to available info

Some test features are not available in production builds of the GuC
firmware. So add the build type field to the available information
that tests can inspect to decide if they should skip or run.

Signed-off-by: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Link: https://lore.kernel.org/r/20250910210237.603576-3-John.C.Harrison@Intel.com