COMPMID-3979 Sanitise Padding Removal epic

* Add missing padding immutability asserts in all relevant CL kernels
* Remove unnecessary zero padding validation tests.

Change-Id: If93f9ccbc988e0286f5e7b135f812141476d5da0
Signed-off-by: SiCong Li <sicong.li@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/4446
Reviewed-by: Gian Marco Iodice <gianmarco.iodice@arm.com>
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/src/core/CL/kernels/CLPoolingLayerKernel.cpp b/src/core/CL/kernels/CLPoolingLayerKernel.cpp
index 905610c..79843cd 100644
--- a/src/core/CL/kernels/CLPoolingLayerKernel.cpp
+++ b/src/core/CL/kernels/CLPoolingLayerKernel.cpp
@@ -216,6 +216,8 @@
 {
     ARM_COMPUTE_ERROR_ON_NULLPTR(input, output);
 
+    auto padding_info = get_padding_info({ input, output, indices });
+
     // Set instance variables
     _input                              = input;
     _output                             = output;
@@ -419,6 +421,8 @@
     _config_id += support::cpp11::to_string(output->info()->dimension(idx_channel));
     _config_id += "_";
     _config_id += lower_string(string_from_data_layout(input->info()->data_layout()));
+
+    ARM_COMPUTE_ERROR_ON(input->info()->data_layout() == DataLayout::NHWC && has_padding_changed(padding_info));
 }
 
 Status CLPoolingLayerKernel::validate(const ITensorInfo *input, const ITensorInfo *output, const PoolingLayerInfo &pool_info, const ITensorInfo *indices)