use 'content' instead of 'source' to increase performance

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This pull-request replaces 'source' parameters with 'content' to increase performance of Puppet Servers / decrease load on Puppet Servers.

When serving (a lot of) agents concurrently using 'content' instead of 'source' mitigates 'attempt to read body out of block' errors.

Error: /Stage[main]/Ipset/File[/usr/local/bin/ipset_sync]: Could not evaluate: Could not retrieve file metadata for puppet:///modules/ipset/ipset_sync: Request to https://<puppetserver>:8140/puppet/v3/file_metadata/modules/ipset/ipset_sync?links=manage&checksum_type=sha256&source_permissions=ignore&environment=stable failed after 583.136 seconds: attempt to read body out of block