Remove explicit connector tool undeferral (#23390)

## Summary
- remove the explicit-connector carveout that kept mentioned app tools
directly exposed instead of deferred
- keep the surviving explicit-mention reconstruction only for analytics,
preserving `codex_app_mentioned` and `codex_app_used.invoke_type`
- trim the now-unused prompt/tool-exposure plumbing and refresh coverage
around always-defer behavior

## Verification
- `just fmt`
- `cargo test -p codex-analytics`
- `cargo test -p codex-core` *(one transient timeout in
`shell_snapshot::tests::macos_zsh_snapshot_includes_sections`; isolated
rerun passed)*
- `cargo test -p codex-core --lib
shell_snapshot::tests::macos_zsh_snapshot_includes_sections`
- `cargo test -p codex-core --test all
explicit_app_mentions_respect_always_defer`
- `cargo test -p codex-core --lib
mcp_tool_exposure::tests::always_defer_feature_defers_apps_too`
- `just fix -p codex-analytics`
- `just fix -p codex-core`

codex-rs/core/src/compact_remote.rs

@@ -1,4 +1,3 @@
-use std::collections::HashSet;
 use std::sync::Arc;
 
 use crate::Prompt;
@@ -174,9 +173,6 @@ async fn run_remote_compact_task_inner_impl(
     let tool_router = built_tools(
         sess.as_ref(),
         turn_context.as_ref(),
-        &prompt_input,
-        &HashSet::new(),
-        /*skills_outcome*/ None,
         &CancellationToken::new(),
     )
     .await?;