Remove newline from query parameters

Base64.encodeToString appends a LF/newline character by default to
the end of the output. This was causing the Android RKP client to
generate "odd" looking URLs. Pass NO_WRAP to the encoder routine so
that we don't ever line-wrap.

Test: atest RkpdAppIntegrationTests RkpdAppHostTests
Bug: 279491835
Change-Id: I2bf699613d377e033de5d7f900b2e181837b7296