fix(infra/k8s): Workaround for nginx crash on pidfile write

Newer versions of nginx apparently hard-crash if they can't write a
PID file in the current directory.

To work around this, some writeable scratch space is created for the
nginx daemon to write its PID to.

infra/kubernetes/nginx/nginx.conf

@@ -1,6 +1,7 @@
 daemon off;
 worker_processes  1;
 error_log stderr;
+pid /run/nginx.pid;
 
 events {
     worker_connections  1024;