Fix duplicate ATen kernel registration in macOS executor_runner

The macOS preset enables both EXECUTORCH_BUILD_KERNELS_OPTIMIZED and
EXECUTORCH_BUILD_EXECUTOR_RUNNER, so the top-level CMake selects
optimized_native_cpu_ops_lib as the runner's ops registration library.
coremldelegate is pulled into the runner's link line through
executorch_backends and force-loaded, and it was also privately linking
portable_ops_lib and portable_kernels whenever
EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER was on. The runner therefore ended
up with optimized_native_cpu_ops_lib and portable_ops_lib both registering
overlapping ATen kernels at static-init time, aborting before main().

Drop the misplaced portable-kernel link from coremldelegate and remove the
now-unused EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER option. The option never
gated building a real CMake runner target; the CoreML executor runner under
examples/apple/coreml/executor_runner is an Xcode project, and the
build_executor_runner.sh script that drives it stages libportable_ops_lib.a
and libportable_kernels.a into examples/apple/coreml/executor_runner/libraries/
where the Xcode project links them directly, independent of
libcoremldelegate.a's link list.

Author: devin-lai

backends/apple/coreml/CMakeLists.txt

@@ -230,12 +230,6 @@ if(APPLE)
 
   executorch_target_link_options_shared_lib(coremldelegate)
 
-  if(EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER)
-    target_link_libraries(
-      coremldelegate PRIVATE portable_ops_lib portable_kernels
-    )
-  endif()
-
   target_compile_options(
     coremldelegate PRIVATE -fobjc-arc -fno-exceptions -x objective-c++
                            -Wno-null-character -Wno-receiver-expr

tools/cmake/preset/default.cmake

@@ -194,10 +194,6 @@ define_overridable_option(
 define_overridable_option(
   EXECUTORCH_BUILD_VGF "Build the Arm VGF backend" BOOL OFF
 )
-define_overridable_option(
-  EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER "Build CoreML executor runner." BOOL
-  OFF
-)
 define_overridable_option(
   EXECUTORCH_BUILD_WASM "Build the ExecuTorch JavaScript API" BOOL OFF
 )

tools/cmake/preset/macos.cmake

@@ -9,4 +9,3 @@ include(${PROJECT_SOURCE_DIR}/tools/cmake/preset/apple_common.cmake)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_EVALUE_UTIL ON)
 set_overridable_option(EXECUTORCH_BUILD_EXTENSION_RUNNER_UTIL ON)
 set_overridable_option(EXECUTORCH_BUILD_EXECUTOR_RUNNER ON)
-set_overridable_option(EXECUTORCH_COREML_BUILD_EXECUTOR_RUNNER ON)