Delete unused weak handle and remove duplicate loads. (#18635)

# Objective

- Cleanup

## Solution

- Remove completely unused weak_handle
(`MESH_PREPROCESS_TYPES_SHADER_HANDLE`). This value is not used
directly, and is never populated.
- Delete multiple loads of `BUILD_INDIRECT_PARAMS_SHADER_HANDLE`. We
load it three times right after one another. This looks to be a
copy-paste error.

## Testing

- None.

crates/bevy_pbr/src/render/gpu_preprocess.rs

@@ -66,9 +66,6 @@ use super::{ShadowView, ViewLightEntities};
 /// The handle to the `mesh_preprocess.wgsl` compute shader.
 pub const MESH_PREPROCESS_SHADER_HANDLE: Handle<Shader> =
     weak_handle!("c8579292-cf92-43b5-9c5a-ec5bd4e44d12");
-/// The handle to the `mesh_preprocess_types.wgsl` compute shader.
-pub const MESH_PREPROCESS_TYPES_SHADER_HANDLE: Handle<Shader> =
-    weak_handle!("06f797ef-a106-4098-9a2e-20a73aa182e2");
 /// The handle to the `reset_indirect_batch_sets.wgsl` compute shader.
 pub const RESET_INDIRECT_BATCH_SETS_SHADER_HANDLE: Handle<Shader> =
     weak_handle!("045fb176-58e2-4e76-b241-7688d761bb23");
@@ -452,18 +449,6 @@ impl Plugin for GpuMeshPreprocessPlugin {
             "build_indirect_params.wgsl",
             Shader::from_wgsl
         );
-        load_internal_asset!(
-            app,
-            BUILD_INDIRECT_PARAMS_SHADER_HANDLE,
-            "build_indirect_params.wgsl",
-            Shader::from_wgsl
-        );
-        load_internal_asset!(
-            app,
-            BUILD_INDIRECT_PARAMS_SHADER_HANDLE,
-            "build_indirect_params.wgsl",
-            Shader::from_wgsl
-        );
     }
 
     fn finish(&self, app: &mut App) {