[system-probe] Add missing system probe settings for parity with helm chart

[xornivore]

What does this PR do?

Adds missing toggles for OOMKill and TCPQueueLength modules as well as collectDNSStats setting.

Motivation

Parity with the helm chart in terms of full set of system probe features.

Additional Notes

Adding unit tests for these and similar features (hello security agent!) becomes rather tedious and results in rather repetitive code, there might be some quick wins in terms of refactoring to use more helper functions and injecting additional volumes, mounts. It would be ideal to keep that refactoring separate from these changes here.

Describe your test plan

Configure DatadogAgent CR with desired features and make sure they are properly enabled:

apiVersion: datadoghq.com/v1alpha1
kind: DatadogAgent
metadata:
  name: datadog-agent
spec:
# ...
  agent:
    # ...
    systemProbe:
      enabled: true
      enableOOMKill: true
      enableTCPQueueLength: true
   # ...

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[codecov-commenter]

Codecov Report

Merging #149 into master will increase coverage by 0.27%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #149      +/-   ##
==========================================
+ Coverage   58.68%   58.96%   +0.27%     
==========================================
  Files          31       31              
  Lines        4909     4942      +33     
==========================================
+ Hits         2881     2914      +33     
  Misses       1814     1814              
  Partials      214      214              

Flag	Coverage Δ
#unittests	58.96% <100.00%> (+0.27%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
pkg/controller/datadogagent/systemprobe.go	100.00% <100.00%> (ø)
pkg/controller/datadogagent/utils.go	82.59% <100.00%> (+0.44%)	⬆️

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[clamoriniere]

I think we are missing the "kernelHeader folder"
@L3n41c could you confirm?

[L3n41c]

Well, the kernel headers are looked for in /lib/modules/$(uname -r)/build which is generally a symlink to /usr/src/kernel-$(uname-r).
So, mounting the modules and src volumes defined here should be fine.
👍🏻

[L3n41c]

Well, the kernel headers are looked for in /lib/modules/$(uname -r)/build which is generally a symlink to /usr/src/kernel-$(uname-r).
So, mounting the modules and src volumes defined here should be fine.
👍🏻