Disable systemd resolved

Fixes flake: 'dial tcp: lookup cdn03.quay.io: no such host'

Okay, doesn't actually fix as in _fix_, just fix as in "sweep it
under the rug". The actual bug is in systemd-resolved, or in the
quay.io/cloudflare.net DNS nameservers, or in the weird specific
setup for cdn03 (it's a CNAME, compared to cdn01/02 which are A).
Maybe a combination of all of the above. I don't care; I just
want the flakes gone. I realize that this makes our testing
environment different from default Fedora, and am okay with
that because I suspect many Fedora users disable systemd-resolved
as SOP.

Signed-off-by: Ed Santiago <santiago@redhat.com>

tests/roles/disable_systemd_resolved/files/disable_systemd_resolved.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+#
+# Excerpted from https://github.com/containers/automation_images/blob/main/systemd_banish.sh
+#
+# Early 2023: https://github.com/containers/podman/issues/16973
+#
+# We see countless instances of "lookup cdn03.quay.io" flakes.
+# Disabling the systemd resolver has completely resolved those,
+# from multiple flakes per day to zero in a month.
+#
+# Opinions differ on the merits of systemd-resolve, but the fact is
+# it breaks our CI testing. Kill it.
+nsswitch=/etc/authselect/nsswitch.conf
+if [[ -e $nsswitch ]]; then
+    if grep -q -E 'hosts:.*resolve' $nsswitch; then
+        echo "Disabling systemd-resolved"
+        sed -i -e 's/^\(hosts: *\).*/\1files dns myhostname/' $nsswitch
+        systemctl disable --now systemd-resolved
+        rm -f /etc/resolv.conf
+
+        # NetworkManager may already be running, or it may not....
+        systemctl start NetworkManager
+        sleep 1
+        systemctl restart NetworkManager
+
+        # ...and it may create resolv.conf upon start/restart, or it
+        # may not. Keep restarting until it does. (Yes, I realize
+        # this is cargocult thinking. Don't care. Not worth the effort
+        # to diagnose and solve properly.)
+        retries=10
+        while ! test -e /etc/resolv.conf;do
+              retries=$((retries - 1))
+              if [[ $retries -eq 0 ]]; then
+                  echo "Timed out waiting for resolv.conf" >&2
+                  echo "...gonna try continuing. Expect failures." >&2
+              fi
+              systemctl restart NetworkManager
+              sleep 5
+        done
+    fi
+fi

tests/roles/disable_systemd_resolved/tasks/main.yml

@@ -0,0 +1,3 @@
+---
+- name: disable systemd resolved
+  script: ./disable_systemd_resolved.sh

tests/test_podman.yml

@@ -7,6 +7,7 @@
   - artifacts: ./artifacts
     rootless_user: testuser
   roles:
+  - role: disable_systemd_resolved
   - role: rootless_user_ready
 
   tasks: