examples: remove redundant C++ standard setting in main component

All examples already set the C++ standard in the project-level
CMakeLists.txt. The main component redundantly sets it again.
As per the ESP-IDF C++ support guide, a component should only
override the C++ version if it intends to use a different one.
We want to keep a consistent version across the project, so
the redundant setting is removed.

examples/controller/main/CMakeLists.txt

@@ -7,5 +7,4 @@ if(CONFIG_SPIFFS_ATTESTATION_TRUST_STORE)
     spiffs_create_partition_image(paa_cert ${CMAKE_SOURCE_DIR}/paa_cert FLASH_IN_PROJECT)
 endif()
 
-set_property(TARGET ${COMPONENT_LIB} PROPERTY CXX_STANDARD 17)
 target_compile_options(${COMPONENT_LIB} PRIVATE "-DCHIP_HAVE_CONFIG_H")