Accept instances hashes on apache and http_check integrations

[asenci]

What does this PR do?

This allows more options to be passed directly to the configuration template, without needing to update the module every time a new option is implemented while keeping it backwards compatible with the current style of parameters.

This also removes one test case from http_check: with headers parameter array (I couldn't find a use case for this on the Datadog integration documentation or code).

Motivation

Using the current method of passing options as parameters to the Puppet module requires a module update every time a new option is added to the Datadog agent integration.

Additional Notes

Describe your test plan

Test cases included on the respective spec files

[albertvaka]

Looking at the tests, there's something in this PR that Puppet 4.6 doesn't like.

[albertvaka]

I spent a bit of time trying to debug the crash on Puppet 4.6 and I managed to track it down to this change which was added in Puppet 4.9.4: puppetlabs/puppet@6bc88d1

Without this change, it fails with undefined method instance?' for nil:NilClass` but I'm not sure why. Maybe it's a good excuse to drop support for Puppet 4.6? :)

[albertvaka]

@asenci I see some activity in your branch :) Do you think you could fix the failing tests on puppet 4.6? Then we could merge this to main.

[asenci]

@asenci I see some activity in your branch :) Do you think you could fix the failing tests on puppet 4.6? Then we could merge this to main.

Sorry for the lack of feedback, we were down a team member for a while and I didn't have much time to work on this.
I'll try to get this sorted by next week. 👍

[asenci]

Hi @albertvaka, I tried everything I could think of, but I couldn't make it work with Puppet 4.6.

It seems to be some weird interaction with the test cases when spec_helper tries to check the resulting file. It passes the tests if you disable some specific checks on datadog_agent_integrations_http_check_spec.rb (mostly related to empty tag testing), but I wasn't able to progress any further with the troubleshooting.

Not sure if there is anything else you would like to try, or if you'd prefer to close the PR?

[albertvaka]

A thousand thanks for all the tests you made, I could see the commits on my Github notifications 🙇 🙇 🙇

I think this change is good and important, so if that's fine for you, let's keep the PR open until either we drop support for 4.6 or someone can help solve the problem on that version.