*: remove io/ioutil as changed in Go 1.16

[AstroProfundis]

What problem does this PR solve?

The package io/ioutil is deprecated in Go 1.16 and been replaced by new os and io packages.

What is changed and how it works?

Since we bumped minimal required Go version to 1.16 in #1151, it's now safe to remove usage of io/ioutil from the code base.

Check List

Tests

• Unit test
• Integration test

Code changes

• Has exported function/method change

Side effects

• Breaking backward compatibility

Release notes:

*: replace `io/ioutil` with `io` and `os` packages

[codecov-io]

Codecov Report

Merging #1153 (83b117f) into master (e92af4f) will decrease coverage by 14.67%.
The diff coverage is 59.79%.

@@             Coverage Diff             @@
##           master    #1153       +/-   ##
===========================================
- Coverage   53.52%   38.84%   -14.68%     
===========================================
  Files         284      256       -28     
  Lines       20299    18898     -1401     
===========================================
- Hits        10865     7341     -3524     
- Misses       7756    10241     +2485     
+ Partials     1678     1316      -362     

Flag	Coverage Δ
cluster	36.40% <55.00%> (-8.63%)	⬇️
dm	?
integrate	38.84% <59.79%> (-9.05%)	⬇️
playground	2.93% <9.37%> (-0.01%)	⬇️
tiup	16.36% <17.80%> (+<0.01%)	⬆️
unittest	?

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

Impacted Files	Coverage Δ
cmd/clean.go	32.35% <0.00%> (ø)
cmd/mirror.go	48.51% <0.00%> (ø)
cmd/status.go	27.02% <0.00%> (ø)
components/playground/monitor.go	0.00% <0.00%> (ø)
components/playground/playground.go	0.00% <0.00%> (ø)
pkg/cluster/ansible/config.go	0.00% <ø> (ø)
pkg/cluster/ansible/inventory.go	0.00% <0.00%> (-54.75%)	⬇️
pkg/cluster/manager/edit_config.go	0.00% <0.00%> (-31.25%)	⬇️
pkg/cluster/spec/drainer.go	58.76% <0.00%> (ø)
pkg/cluster/spec/pd.go	56.02% <0.00%> (-12.05%)	⬇️
... and 187 more

---

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[lucklove]

/lgtm

[ti-chi-bot]

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• lucklove

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[lucklove]

/merge

[ti-chi-bot]

This pull request has been accepted and is ready to merge.

Commit hash: 63c6fd7

[ti-chi-bot]

@AstroProfundis: Your PR was out of date, I have automatically updated it for you.

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