bazel build install-devcore fails with rootless podman 3.4.4 (Ubuntu 22.04):

Error: error configuring CNI network plugin: exec: "nsenter": executable file not found in $PATH

nsenter is installed. The MongoInstallRule action runs under exec env -, so it has an empty environment and no PATH. _container_runtime_env in linux_container_action_wrapper.py copies os.environ into the environment of its podman calls. Podman 3.4.4 looks up nsenter through PATH when setting up CNI networking, so the call exits with 125.

_container_runtime_env now applies setdefault("PATH", _PODMAN_DEFAULT_PATH) using the standard system path. It only affects the podman client process, not the environment the build tool sees inside the container. linux_container_action_wrapper_test.py gains a regression test for the empty-environment case.

Testing: bazel build install-devcore now succeeds, and //bazel/toolchains/cc/mongo_linux:linux_container_action_wrapper_test passes.