test(recovery): reap detached tree in live_process/dead_process too

Repeated/root verification of the prior fix surfaced two more recovery tests
that leak the same detached inner tree (2 procs each, every run):
- recovery_with_live_process cleans up via production remove(force=true), which
  only signals the recorded outer bwrap;
- recovery_with_dead_process manually SIGKILLs the recorded outer bwrap.
Both leave the inner pid-ns bwrap + shim + VM alive (post-#851).

Arm a ShimReaper (pkill -9 -f <box id>) in both, matching the two pid-file
tests, so each reaps its whole tree on drop.

Verified as root, repeated: pid-file tests x10 -> 0 leak; full recovery suite
x3 -> 9 pass, 0 leak each. Compiles (--features krun,gvproxy); cargo fmt clean.

The underlying production leak (stop / rm -f only signal the outer bwrap, so a
detached box's inner tree survives; cgroup.kill reaps it) is a separate
runtime-side bug, handled in its own draft PR — this commit only keeps the
recovery suite from leaking.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: G4614

src/boxlite/tests/recovery.rs

@@ -56,6 +56,9 @@ async fn recovery_with_live_process() {
     let home = boxlite_test_utils::home::PerTestBoxHome::new();
     let box_id: String;
     let original_pid: u32;
+    // Detached box: the teardown `remove(force)` only signals the recorded
+    // outer bwrap, leaving the inner pid-ns tree alive (see ShimReaper).
+    let mut reaper = ShimReaper(None);
 
     // Create box with detach=true
     {
@@ -78,6 +81,7 @@ async fn recovery_with_live_process() {
 
         let _ = handle.exec(BoxCommand::new("sleep").args(["300"])).await;
         box_id = handle.id().to_string();
+        reaper.0 = Some(box_id.clone());
 
         let pf = pid_file_path(&home.path, &box_id);
         original_pid = PidFileReader::at(&pf).read().map(|r| r.pid).unwrap();
@@ -109,6 +113,9 @@ async fn recovery_with_live_process() {
 async fn recovery_with_dead_process() {
     let home = boxlite_test_utils::home::PerTestBoxHome::new();
     let box_id: String;
+    // Detached box: SIGKILLing the recorded outer bwrap below leaves the inner
+    // pid-ns tree alive; the reaper kills it by id on drop (see ShimReaper).
+    let mut reaper = ShimReaper(None);
 
     // Create box
     {
@@ -131,6 +138,7 @@ async fn recovery_with_dead_process() {
 
         let _ = handle.exec(BoxCommand::new("sleep").args(["300"])).await;
         box_id = handle.id().to_string();
+        reaper.0 = Some(box_id.clone());
 
         let pf = pid_file_path(&home.path, &box_id);
         let original_pid = PidFileReader::at(&pf).read().map(|r| r.pid).unwrap();