Continuation of SERVER-131029, which migrated the basic, SEARCH_META, and sharded-topology-specific mocked $search tests to the e2e suites across four PRs. This ticket covers the remaining migratable groups from that ticket's classification (tests asserting the mongod<->mongot wire protocol, auth/SSL topology, or mongotmock itself stay mocked and are dispositioned under SERVER-131069). All files are in jstests/with_mongot/search_mocked/.

Remaining groups

• Explain family — search_explain.js, search_explain_execution_stats.js, search_meta_explain.js, search_meta_var_explain.js, sharded_search_explain.js, sharded_search_explain_execution_stats.js, sharded_search_meta_explain.js. Largely a dedup audit: substantial coverage already exists in jstests/with_mongot/e2e/explain_execution_stats/. Mongot explain-only vs explain+cursor response variants are mock-driven and stay mocked.
• Sequence tokens — search_sequence_token.js, search_sequence_token_in_lookup.js, search_sequence_token_outside_project.js, sharded_search_sequence_token.js. Requires real mongot to emit searchSequenceTokens (supported; verify mongot-localdev behavior).
• Stored source — search_stored_fields.js (returnStoredSource works against real mongot, unlike vectorSearch at the time of SERVER-117449).
• $unionWith/$lookup — search_union_with_lookup.js, search_sharded_union_with_lookup.js. Partial overlap with e2e/explain_execution_stats/search_union_with_lookup_explain.js and e2e/views/search/.
• Sharded core collapse decisions — sharded_search.js, sharded_search_random_dataset.js, shard_limit_test.js, sharded_sort.js, sharded_sort_subpipeline.js, sharded_hybrid_search.js. Much of this collapses into existing base e2e tests running in the sharded passthrough suites (SERVER-117449 precedent: sharded_vector_search.js was not migrated, just deleted).
• Search index commands — text_search_index_commands.js, multi_sharded_text_search_index_commands.js. Happy paths overlap e2e/views/search_index_commands.js and e2e_infrastructure_tests/; error cases inject unavailable mock hosts and stay mocked.
• Query stats — sharded_search_query_stats.js, enable_query_stats_on_shard_servers.js. Note: sharded $searchMeta query-stats migration is blocked on SERVER-131073.
• Misc — search_and_lookup_with_cache.js (plan cache), search_read_concurrency.js (mongod failpoint), internal_search_mongot_remote.js (largely duplicates the migrated basic test), list_search_indexes_deprecated.js, search_view.js (dedup vs e2e/views/search/), sharded_search_requiresSearchMetaCursor_double_search.js (system.profile-based; overlaps e2e/sharding_no_passthrough/sharded_search_requiresSearchMetaCursor.js).

Follow the conventions established in the SERVER-131029 PRs: mochalite style, coverage-summary headers, jsTestName() + "_index" index names, real count/facet metadata, TODO (SERVER-131069) markers on migrated/covered mocked files noting any coverage intentionally left behind.