scripts: west: Check for sysbuild flag when parsing test item

If build is used with -T option, sysbuild flag was ignored
neverthelesss being present in sample.yaml/testcase.yaml
file.

Signed-off-by: Emil Obalski <Emil.Obalski@nordicsemi.no>

scripts/west_commands/build.py

@@ -290,6 +290,7 @@ class Build(Forceable):
                     self.args.cmake_opts.extend(args)
                 else:
                     self.args.cmake_opts = args
+            self.args.sysbuild = item.get('sysbuild')
         return found_test_metadata
 
     def _sanity_precheck(self):