Some time ago a new shim for nRF UARTE was added (uart_nrfx_uarte2.c)
which used nrfx_uarte.c driver underneath. It was supposed to support
nrf54x platforms. However, later on legacy driver (uart_nrfx_uarte.c)
was extended to support nrf54x platforms and it takes less code size,
has better performance and more features. Shim uart_nrfx_uarte2 will
no longer be supported. As new shim is the default and there is a
Kconfig to pick the legacy shim (CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=y)
it cannot be deprecated in the normal way. Additional Kconfig option
is created (DEPRECATED_UART_NRFX_UARTE_LEGACY_SHIM) which is enabled
if CONFIG_UART_NRFX_UARTE_LEGACY_SHIM=n and it selects DEPRECATED.
A warning was also added to the CMakeLists.txt.
Patch removes use CONFIG_UART_NRFX_UARTE_LEGACY_SHIM in tests.
Signed-off-by: Krzysztof Chruściński <krzysztof.chruscinski@nordicsemi.no>