[IMP] better detection of search engine

[sebastienbeau]

For using a search engine we check that

• the schema have the key
• the data is configured (check application id for algolia and url for elasctic)

Now if you remove one of the search engine in the metafield, the search engine is not used anymore. If you remove the application_id of algolia configuration or the url for elastic, this search engine are not used anymore