snapuserd: Don't statically link outside of ramdisk.

Also, remove snapuserd from the vendor ramdisk since this isn't used
anymore.

Bug: 345158294
Test: ldd snapuserd_ramdisk and system/bin/snapuserd
      apply full OTA on aosp_cf
Change-Id: I2c2ad1458d67a8449c548e22660f523ba9c86849