tests: Use system utils outside of the test environment

The code to pick up the utilities from the test environment would fail
if the environment variables are not set. In that case, we can just use
the binary name and rely on PATH though.

tests/fprintd.py

@@ -1424,6 +1424,10 @@ class FPrintdUtilsTest(FPrintdVirtualDeviceBaseTest):
                 print('Testing JHBuild version')
                 jhbuild_prefix = os.environ['JHBUILD_PREFIX']
                 path = os.path.join(jhbuild_prefix, 'bin', util_bin)
+            else:
+                # Assume it is in path
+                utils[util] = util_bin
+                continue
 
             assert os.path.exists(path), 'failed to find {} in {}'.format(util, path)
             utils[util] = path