[SYCL][NFC] Remove sampled_image_accessor and unsampled_image_accessor from test plan for free function kernels extension (#19086)

This PR removes `sampled_image_accessor` and unsampled_image_accessor
from planned test regarding structs that containing special types such
as `accessor` and `local_accessor`.
It's fix because it was not removed in previous PR:
intel/llvm#18994

---------

Co-authored-by: Steffen Larsen <steffen.larsen@intel.com>

Author: dyniols

sycl/test-e2e/FreeFunctionKernels/test-plan.md

@@ -192,11 +192,10 @@ as kernel parameter to free function kernel and use it within kernel.
 A series of checks should be performed that we can pass `local_accessor` 
 as kernel parameter to free function kernel and use it within kernel.
 
-#### Test structs that contain one of the following `accessor`, `local_accessor`, `sampled_image_accessor` or `unsampled_image_accessor` types when used as kernel parameter:
+#### Test structs that contain either `accessor` or `local_accessor` when used as kernel parameter:
 A series of checks should be performed that we can pass struct that contain 
-one of the following `accessor`, `local_accessor`, `sampled_image_accessor` or 
-`unsampled_image_accessor` types as kernel parameter to free function kernel 
-and use it within kernel.
+either `accessor` or `local_accessor` as kernel parameters 
+to free function kernel and use it within kernel.
 
 #### Test `struct` defined at namespace scope as kernel parameter:
 A series of checks should be performed that we can pass `struct` as kernel