KEYCLOAK-15079 Resolve two test failures
This PR resolves these test failures, currently on master:
```
Tests run: 5, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 38.833 sec <<< FAILURE!
checkExternalLinks(org.keycloak.documentation.test.SecuringAppsTest) Time elapsed: 38.723 sec <<< FAILURE!
* http://undertow.io/ (invalid redirect to https://undertow.io/)
Tests run: 5, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.999 sec <<< FAILURE!
checkVariables(org.keycloak.documentation.test.GettingStartedTest) Time elapsed: 0.004 sec <<< FAILURE!
* context
Running org.keycloak.documentation.test.ServerInstallationTest
```
And these product test failures:
```
Running org.keycloak.documentation.test.GettingStartedTest
Tests run: 5, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 0.79 sec <<< FAILURE!
checkExternalLinks(org.keycloak.documentation.test.GettingStartedTest) Time elapsed: 0.767 sec <<< FAILURE!
* http://access.redhat.com/documentation/en-us/red_hat_single_sign-on/7.4.1/ (invalid redirect to https://access.redhat.com/documentation/en-us/red_hat_single_sign-on/7.4.1/)
Running org.keycloak.documentation.test.OpenShiftTest
Tests run: 5, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 8.502 sec <<< FAILURE!
checkExternalLinks(org.keycloak.documentation.test.OpenShiftTest) Time elapsed: 8.404 sec <<< FAILURE!
* https://access.redhat.com/documentation/en-us/red_hat_single_sign-on/7.4.1/html-single/red_hat_single_sign-on_for_openshift_on_openj9/ (invalid status code 404)
```
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