Remove DD_HOSTNAME from agent and move it back to check runner

[carloscastrojumo]

What does this PR do?

Remove DD_HOSTNAME as environment variable from DataDog agent and put it back to check runner.

Motivation

DD_HOSTNAME was removed from check runner and added by mistake in the agent in this PR #3

Additional Notes

Add dependency for bin/operator-sdk in make container and make e2e commands.

[codecov-commenter]

Codecov Report

Merging #139 into master will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #139   +/-   ##
=======================================
  Coverage   58.02%   58.02%           
=======================================
  Files          31       31           
  Lines        4610     4610           
=======================================
  Hits         2675     2675           
  Misses       1739     1739           
  Partials      196      196           

Flag	Coverage Δ
#unittests	58.02% <100.00%> (ø)

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Impacted Files	Coverage Δ
pkg/controller/datadogagent/utils.go	83.16% <ø> (-0.12%)	⬇️
pkg/controller/datadogagent/clusterchecksrunner.go	72.63% <100.00%> (+0.63%)	⬆️

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[ahmed-mez]

Hi @carloscastrojumo thanks for the contribution.

Actually DD_HOSTNAME should be set explicitly only for the datadog-cluster-checks-runner. (see the helm chart for reference)

We shouldn't set the hostname for the datadog-agent and it's the case currently because of an oversight I believe, introduced by mistake in the refactoring done by this PR #3

The agent has automatic mechanisms to discover the node name, the option should be only used in particular cases - that's why the option exists.

Would you be interested in fixing it by removing DD_HOSTNAME from the agent, and move it to the check runner only?

Thanks!

[carloscastrojumo]

Hi @ahmed-mez thank you for the review.

As suggested, updated my PR to remove the DD_HOSTNAME from agent and cluster agent and just introduce it back to check runner.

[ahmed-mez]

@carloscastrojumo that's great! could you please update the PR's title and description accordingly? thanks!