twister: runner: --prep-artifacts-for-testing protection

need add protection when check with sysbuild filter out
application, the domains is NULL

fixes: #87163

Signed-off-by: Hake Huang <hake.huang@oss.nxp.com>

Author: hakehuang

scripts/pylib/twister/twisterlib/runner.py

@@ -1350,7 +1350,7 @@ def cleanup_device_testing_artifacts(self):
         files_to_keep = self._get_binaries()
         files_to_keep.append(os.path.join('zephyr', 'runners.yaml'))
 
-        if self.instance.sysbuild:
+        if self.instance.sysbuild and self.instance.domains:
             files_to_keep.append('domains.yaml')
             for domain in self.instance.domains.get_domains():
                 files_to_keep += self._get_artifact_allow_list_for_domain(domain.name)
@@ -1390,7 +1390,7 @@ def _get_binaries(self) -> list[str]:
         # Get binaries for a single-domain build
         binaries += self._get_binaries_from_runners()
         # Get binaries in the case of a multiple-domain build
-        if self.instance.sysbuild:
+        if self.instance.sysbuild and self.instance.domains:
             for domain in self.instance.domains.get_domains():
                 binaries += self._get_binaries_from_runners(domain.name)