[dx] better check for processes in self destructing enviroments (#1140)

Signed-off-by: Andrei Kvapil <kvapss@gmail.com>

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## What this PR does


### Release note

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```release-note
[dx] better check for processes in self destructing enviroments
```

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Chores**
* Updated system image to include additional utilities for process
management.

* **Refactor**
* Simplified internal process filtering to improve reliability and
maintainability.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

packages/core/testing/images/e2e-sandbox/Dockerfile

@@ -9,7 +9,7 @@ ARG TARGETOS
 ARG TARGETARCH
 
 RUN apt update -q
-RUN apt install -yq --no-install-recommends genisoimage ca-certificates qemu-kvm qemu-utils iproute2 iptables wget xz-utils netcat curl jq make git
+RUN apt install -yq --no-install-recommends psmisc genisoimage ca-certificates qemu-kvm qemu-utils iproute2 iptables wget xz-utils netcat curl jq make git
 RUN curl -sSL "https://github.com/siderolabs/talos/releases/download/v${TALOSCTL_VERSION}/talosctl-${TARGETOS}-${TARGETARCH}" -o /usr/local/bin/talosctl \
  && chmod +x /usr/local/bin/talosctl
 RUN curl -sSL "https://dl.k8s.io/release/v${KUBECTL_VERSION}/bin/${TARGETOS}/${TARGETARCH}/kubectl" -o /usr/local/bin/kubectl \

packages/core/testing/images/e2e-sandbox/entrypoint.sh

@@ -17,36 +17,16 @@ while [ $# -gt 0 ]; do
   esac
 done
 
-ALL_PROCS=$(ps -eo pid=,ppid=,comm=)
-
-get_descendants() {
-  PARENT="$1"
-  echo "$PARENT"
-  echo "$ALL_PROCS" | while read -r PID PPID CMD; do
-    PID=$(echo "$PID" | tr -d ' ')
-    PPID=$(echo "$PPID" | tr -d ' ')
-    if [ "$PPID" = "$PARENT" ]; then
-      echo "$PID"
-      get_descendants "$PID"
-    fi
-  done
-}
-
-is_own_tree() {
-  PID="$1"
-  echo "$DESCENDANTS" | grep -q -x "$PID"
-}
-
 check_once() {
-  DESCENDANTS="$(get_descendants "$SELF_PID" | sort -u)"
+  OWN_PIDS=$(pstree -p $$ | grep -o '[0-9]\+' | sort -u)
+  ALL_PROCS=$(ps -eo pid=,comm=)
+
   EXTERNAL_PIDS=$(
-    echo "$ALL_PROCS" | while read -r PID PPID CMD; do
+    echo "$ALL_PROCS" | while read -r PID CMD; do
       PID=$(echo "$PID" | tr -d ' ')
       CMD=$(echo "$CMD" | tr -d ' ')
 
-      if is_own_tree "$PID"; then
-        continue
-      fi
+      echo "$OWN_PIDS" | grep -q -x "$PID" && continue
 
       case "$CMD" in
         *qemu*) continue ;;