test: set maxWorkers for jest to prevent freezes

This sets the maxWorkers in the Jest config to prevent accidental
computer lock-ups/freezes when running tests, because the default is
using the maximum of available resources.

Author: dominikvagner

jest.config.js

@@ -16,4 +16,5 @@ module.exports = {
   transformIgnorePatterns: [
     '<rootDir>/node_modules/(?!(@patternfly/react-core/|@patternfly/react-icons/|@redhat-cloud-services|@openshift|lodash-es|@patternfly/react-table|@patternfly/react-tokens|p-all)).*$',
   ],
+  maxWorkers: 4,
 };