Remove encryption test from profile owner provisioning test.

After b/17881324 (ag/569169), it is no longer possible to know if
full disk encryption is enabled or not, because an encryption-enabled
device without PIN/pattern is treated as not-encrypted by DPM API,
which is what profile owner provisioning mandates.

Bug: 17384646
Change-Id: I4acacf8e8059b288e49b105b24ae4a8c9781477f