chore: hardlink compat cachedir

with kubernetes/puppet deployment, we are mounting /etc/puppetlabs/code
into a PVC. g10k hardlinks. therefore, we need the g10k cache in the
same PVC.

- set cachedir to a hardlink compat path for kubernetes

r10k.yaml

@@ -1,5 +1,5 @@
 # The location to use for storing cached Git repos
-:cachedir: '/opt/puppetlabs/cache/r10k'
+:cachedir: '/etc/puppetlabs/code/.g10k/cachedir'
 
 # A list of git repositories to create
 :sources: