puppet: wal-g is a tarball with a single file, not a directory.

5db55c38dc switched from `ensure => present` to the more specific
`ensure => directory` on the premise that tarballs would result in
more than one file being copied out of them.  However, we only extract
a single file from the wal-g tarball, and install it at the output
path.  The new rule attempts to replace it with an empty directory
after extraction.

Switch back to `ensure => present` for the tarball codepath.

puppet/zulip/manifests/external_dep.pp

@@ -42,7 +42,7 @@ define zulip::external_dep(
       before       => File[$path],
     }
     file { $path:
-      ensure => directory,
+      ensure => present,
     }
   }