Add frontend test for metadata search

Currently, the "search in metadata (instead of URL)" option of the archive search is not tested by frontend tests.

To fix this, we need to:

1. Fill the indexer storage with some test metadata; either by inserting it directly or by calling a Metadata Indexer, see swh-web/swh/web/tests/data.py
2. Write the test itself in cypress/integration/origin-search.spec.js that checks there's a result when searching for a subset of this metadata

---

Migrated from T2285 (view on Phabricator)