Drop ioutil package.

[zhanluxianshen]

Describe what this PR does / why we need it

Drop ioutil package.
As it is deprecation , and can be replaced well.

Deprecated: As of Go 1.16, the same functionality is now 
provided by package [io](https://pkg.go.dev/io) 
or package [os](https://pkg.go.dev/os), 
and those implementations should be preferred in new code

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