(#13261) Add real examples to smoke tests.

This commit modifies some smoke tests with real-world usage examples
instead of providing things like 'foo' that the module user must
replace in order to conduct a smoke test or try out example functionality.

tests/builddep.pp

@@ -1,2 +1,2 @@
 class { 'apt': }
-apt::builddep{ 'foo': }
+apt::builddep{ 'glusterfs-server': }

tests/ppa.pp

@@ -1,2 +1,4 @@
 class { 'apt': }
-apt::ppa{ 'foo': }
+
+# Example declaration of an Apt PPA
+apt::ppa{ 'ppa:openstack-ppa/bleeding-edge': }

tests/release.pp

@@ -1,4 +1,4 @@
 class { 'apt': }
 class { 'apt::release':
-  release_id => 'foo'
+  release_id => 'karmic'
 }

tests/source.pp

@@ -2,6 +2,7 @@
 class { 'apt': }
 
 # Install the puppetlabs apt source
+# Release is automatically obtained from lsbdistcodename fact if available.
 apt::source { 'puppetlabs':
   location   => 'http://apt.puppetlabs.com',
   repos      => 'main',