Wrong assert for UseCompressedOops in aarch64 Copy::conjoint_oops_atomic implementation

The assert for UseCompressedOops in aarch64 Copy::conjoint_oops_atomic implementation is wrong.

The method is supposed to be called for copying (uncompressed) oops only like the similar methods even if UncompressedOops is true.

This is a leftover change from JDK-8166314, as the main issue described there has been fixed earlier.