`labgrid_test` transfers unnecessary runfiles

See #6 (comment 144970).

How to reproduce

Add raise Exception(f"runfiles dir {self.runfiles_dir} list {os.listdir(self.runfiles_dir)}") to this line:

if upload.include_runfiles:
                src_runfiles = local.with_suffix(".runfiles")
                dest_runfiles = remote.with_suffix(".runfiles")
                if Path(src_runfiles).exists():
                    self.transfer.put(f"{src_runfiles}", f"{dest_runfiles}")
                elif self.runfiles_dir is not None:
                    raise Exception(f"runfiles dir {self.runfiles_dir} list {os.listdir(self.runfiles_dir)}")
                    self.transfer.put(f"{self.runfiles_dir}", f"{dest_runfiles}")

Then run bazel test --sandbox_debug //toolchain/config/qemu:test-amd64 , this will show you the runfiles dir that is being transferred. You will see that the qemu image is being transferred test-amd64.runfiles/rules_labgrid~/qemu/debian/image/resized.qcow2 , and the qemu bin test-amd64.runfiles/rules_labgrid~~_repo_rules~resolved-qemu-system/resolved-qemu-system/qemu-system-x86_64 .