samples: bluetooth: Convert peripheral_hr sample.yaml to use depends_on

Converts the Bluetooth peripheral_hr sample.yaml to select boards for
the frdm_kw41z shield configuration by depending on the arduino_serial
feature instead of using an explicit platform_allow list. This will
enable twister to automatically select new boards that add support for
an Arduino serial port.

Signed-off-by: Maureen Helm <maureen.helm@nxp.com>