samples/tests: reduce ram & code size for failing tests on nRF5x boards

These samples/tests fail to build on some of the nRF5x platforms.  We
don't need Bluetooth enabled for these tests so we can reduce footprint
by turning it off.

Change-Id: I87e62a1d70f80d2bc22414d6a9e591e36ad9fa06
Signed-off-by: Kumar Gala <kumar.gala@linaro.org>