Migrate away from deprecated ioutil

[sebrandon1]

ioutil has been deprecated since Go 1.16: https://go.dev/doc/go1.16#ioutil

Tracking issue: redhat-best-practices-for-k8s/telco-bot#52

Migration from deprecated ioutil functions:

• Replaced ioutil.TempDir with os.MkdirTemp and ioutil.WriteFile with os.WriteFile in the createFiles method of cloudinit.go to create temporary directories and write files. [1] [2]
• Replaced ioutil.TempFile with os.CreateTemp in the createFile method of ignition.go for creating temporary files. [1] [2]

[openshift-ci]

@sebrandon1: The following tests failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/unit	71d88cc	link	true	/test unit
ci/prow/verify-deps	71d88cc	link	true	/test verify-deps
ci/prow/govet	71d88cc	link	true	/test govet

Full PR test history. Your PR dashboard.

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[openshift-bot]

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/lifecycle stale

[cfergeau]

/lgtm
/approve

[openshift-ci]

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