This causes the following build errors:
/__w/gsoc-2022-arduino-core/gsoc-2022-arduino-core/Arduino-Zephyr-API/samples/i2cdemo/prj.conf:2: warning: attempt to assign the value 'y' to the undefined symbol CPLUSPLUS
Hence, remove it from all samples as it is no longer needed.
This causes the following build errors: /__w/gsoc-2022-arduino-core/gsoc-2022-arduino-core/Arduino-Zephyr-API/samples/i2cdemo/prj.conf:2: warning: attempt to assign the value 'y' to the undefined symbol CPLUSPLUS
Hence, remove it from all samples as it is no longer needed.