Corrected OpenSearch.

| Q             | A
| ------------- | ---
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | ---
| Fixed tickets | ---
| Refs tickets  | ---
| License       | MIT
| Doc PR        | ---

This corrects some issues with the OpenSearch implementation:
- made it working with shorturls.
- fixed typos `opensearchEnable` vs. `opensearchEnabled`.
- made sure the event listener runs on every page load.