Solr `findAllRequestAdapter` generates invalid JSON API syntax for collapse filter

[danieleguido]

The findAllRequestAdapter method is generating incorrect Solr JSON API syntax when using the collapse query parser. It's placing the {!collapse} directive directly in the filter field combined with AND clauses, which prevents the collapse functionality from working.

The method currently generates:

{
  query: "*:*",
  filter: "{!collapse field=meta_issue_id_s} AND meta_journal_s:NZZ",
  // ... other params
}

This results in documents not being collapsed as expected, because the collapse parser is not being properly recognized.
The collapse query parser should be placed in params.fq (filter query), separate from regular filters:

{
  query: "*:*",
  filter: "meta_journal_s:NZZ",
  params: {
    fq: "{!collapse field=meta_issue_id_s}"
  }
}