Set ipdb as the breakpoint callback (#22135)

Allows inserting breakpoint() inside code to debug with ipdb

docker-compose.yml

@@ -12,6 +12,7 @@ x-env-mapping: &env
     - OLYMPIA_SITE_URL=http://olympia.test
     - PYTHONDONTWRITEBYTECODE=1
     - PYTHONUNBUFFERED=1
+    - PYTHONBREAKPOINT=ipdb.set_trace
     - TERM=xterm-256color
     - CIRCLECI=${CIRCLECI}
     - HISTFILE=/data/olympia/docker/artifacts/bash_history