[SettingsProvider] make nfc_payment_default_component readable

App processes might need to read the Settings value using system code.
Therefore this key is @hide but should be @Readable.

BUG: 191519696
Test: atest android.appsecurity.cts.ReadableSettingsFieldsTest
Change-Id: Idf1512ebf3487d74a18ad2dc13ee7cbb2c7643d0