dcm2niix - Do consider exit 1 to be an error

Based on information in
rordenlab/dcm2niix#733 (comment)

> Exit code 0 is for success, exit code 1 is the undefined error.

Handling of exit 1 as successful was added in 6ecd4a9
AKA 1.0.2~2^2~13

nipype/interfaces/dcm2nii.py

@@ -446,8 +446,7 @@ def _format_arg(self, opt, spec, val):
         return super()._format_arg(opt, spec, val)
 
     def _run_interface(self, runtime):
-        # may use return code 1 despite conversion
-        runtime = super()._run_interface(runtime, correct_return_codes=(0, 1))
+        runtime = super()._run_interface(runtime)
         self._parse_files(self._parse_stdout(runtime.stdout))
         return runtime