lang: core: embedded: provisioner: Handle spurious failures

Not sure why this happen, I think it's just random network blips. Simple
retry should be used for now.

lang/core/embedded/provisioner/files/kickstart.ks.tmpl

@@ -100,7 +100,7 @@ repo --name="{{ $name }}" --baseurl="{{ $baseurl }}"
 #
 #	packages
 #
-%packages
+%packages --retries 3 # handle spurious failures
 @core
 @standard
 @hardware-support