Add parameter to manage the content of log4j2.properties

[h-haaks]

Pull Request (PR) description

Add a parameter to manage the content of the log4j config file
Very simple solution that just replaces the entire content of the file.

This PR fixes review comments in #1234 so that we can get this merged before the next release.

This Pull Request (PR) fixes the following issues

• Fixes log4j config, how to add custom appender #529
• Fixes Same template for both logging.yml and log4j2.properties #907
• Fixes ESJsonLayout as layout type #1056
• Fixes why was log4j2.properties.erb configuration commented ? #1200

Replace Opened PR

• Add new support for logging (log4j2.properties) #1234

[h-haaks]

There is something really strange going on in this file...
It has a double set of on_supported_os blocks, and I don't thing any of the tests in the second block is ran at all.

[h-haaks]

I tried to figure out where to add some acceptance testing for this, but I have no idea where to put them without creating a full shared examples file setup.
Decided not to do that here.

[h-haaks]

I'll fixup commits before merge.

[kenyon]

Suggested change

	it {
	expect(subject).to contain_file('/etc/elasticsearch/log4j2.properties').
	with(ensure: 'file', content: "# Content Line 1\n# Content Line 2")
	}
	it do
	expect(subject).to contain_file('/etc/elasticsearch/log4j2.properties').
	with(ensure: 'file', content: "# Content Line 1\n# Content Line 2")
	end

[h-haaks]

True, multiline ruby blocks should use do..end.
But the entire module is written like this and I don't want to brake that pattern in just one test.
No rubocop autocorrect either ..