Fix: prevent Solr initialization from clearing index data

[mdorf]

Summary

Prevent Solr connector initialization from clearing existing index documents as a side effect of force: true.

Changes

• Update Solr schema initialization so it does not clear index data by default
• Add an explicit destructive schema reset path via reset_schema!
• Preserve existing documents when SolrConnector#init(true) is called
• Add regression coverage proving forced initialization does not delete indexed documents

Why

force: true was used by callers to refresh/reinitialize Solr connections and schema state. Before this change, that path called init_schema, which unconditionally cleared all documents from the resolved Solr collection.

For alias-backed search collections, this could wipe the physical collection behind an alias during routine indexing workflows.

Verification

Added regression coverage in test/solr/test_solr.rb:

• test_force_init_preserves_existing_documents indexes a document, calls SolrConnector#init(true), and asserts the document remains in the collection.

Targeted test run:

bundle exec rake test TEST="./test/solr/test_solr.rb" TESTOPTS="--verbose --name=test_force_init_preserves_existing_documents"