tests: fix qvm-copy-to-vm test
tests: fix qvm-copy-to-vm test

Make the check if remote file wasn't removed meaningful. Previously the
user didn't have permission to remote the source file, so even if the
tool would try, it would fail.

QubesOS/qubes-core-admin,QubesOS/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,marmarek/qubes-core-admin,QubesOS/qubes-core-admin