Fix CTS Verifier NFC Test

Explicitly clear NFC user restriction at the beginning of the test,
instead of assuming it's off by default.  Restore original restriction
value at the end of the test.  Just send simple text instead of an image
file in order to avoid timeouts, since the content of the message isn't
relevant for testing the restriction.

Fixes: 70628480
Test: Cts Verifier -> BYOD Managed Provisioning -> Disable Nfc beam
Change-Id: Ia58321c658d16462ff7b2c9f0baeb4dedc99fa26
2 files changed