Remove last batch of easy 'six' dependencies

[iliakur]

What does this PR do?

After this all we have left is a more complicated spark case, then the base check and tooling (datadog_checks_dev).

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• Changelog entries must be created for modifications to shipped code
• Add the qa/skip-qa label if the PR doesn't need to be tested during QA.
• If you need to backport this PR to another branch, you can add the backport/<branch-name> label to the PR and it will automatically open a backport PR once this one is merged

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 90.20%. Comparing base (6faa14c) to head (d7f6001).
Report is 1 commits behind head on master.

Additional details and impacted files

Flag	Coverage Δ
activemq	?
cassandra	?
citrix_hypervisor	87.50% <100.00%> (ø)
gearmand	77.84% <100.00%> (+0.82%)	⬆️
hive	?
hivemq	?
ignite	?
jboss_wildfly	?
kafka	?
network	93.47% <100.00%> (-0.01%)	⬇️
postgres	93.21% <100.00%> (+3.42%)	⬆️
presto	?
solr	?

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