Require absolute paths for test SQLite configuration (#34411)

## Why

`SqliteConfig` stores its home as an `AbsolutePathBuf`, but its test constructor
previously accepted a `PathBuf` and checked the absolute-path invariant at
runtime.

## What changed

- Make `SqliteConfig::new_for_testing` accept an `AbsolutePathBuf` directly,
  removing its fallible conversion and `expect`.
- Update SQLite test setup to convert temporary directory paths with
  `PathExt::abs` at each call site.

GitOrigin-RevId: 93585b9aea805e2449b3465ac20eeb39417ed555

codex-rs/state/src/runtime/remote_control.rs

@@ -158,6 +158,7 @@ mod tests {
     use super::test_support::unique_temp_dir;
     use crate::migrations::STATE_MIGRATOR;
     use crate::state_db_path;
+    use codex_utils_absolute_path::test_support::PathExt;
     use pretty_assertions::assert_eq;
     use sqlx::migrate::Migrator;
     use std::borrow::Cow;
@@ -336,7 +337,7 @@ mod tests {
             table_name: STATE_MIGRATOR.table_name.clone(),
             create_schemas: STATE_MIGRATOR.create_schemas.clone(),
         };
-        let pool = crate::SqliteConfig::new_for_testing(codex_home.clone())
+        let pool = crate::SqliteConfig::new_for_testing(codex_home.as_path().abs())
             .open_read_write_pool(&state_db_path(codex_home.as_path()))
             .await
             .expect("open old state db");