Remove shlex

[AlexandreYang]

What does this PR do?

Remove shlex

Motivation

Not available on windows.

Additional Notes

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #5064 into master will increase coverage by 6.26%.
The diff coverage is 100%.

Impacted Files	Coverage Δ
gunicorn/datadog_checks/gunicorn/gunicorn.py	84.31% <100%> (-0.16%)	⬇️
gunicorn/tests/test_check.py	88.23% <0%> (ø)	⬆️
gunicorn/datadog_checks/gunicorn/__about__.py	100% <0%> (ø)	⬆️
gunicorn/tests/common.py	100% <0%> (ø)	⬆️
gunicorn/datadog_checks/gunicorn/__init__.py	100% <0%> (ø)	⬆️
gunicorn/tests/test_unit.py	100% <0%> (ø)	⬆️
gunicorn/tests/test_metadata.py	100% <0%> (ø)	⬆️
vertica/tests/metrics.py
...checks_dev/tests/plugin/test_environment_runner.py
... and 855 more