Add -automaxprocs flag for configuring GOMAXPROCS

[nixpanic]

What type of PR is this?

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/kind api-change
/kind bug
/kind cleanup
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/kind documentation
/kind failing-test

/kind feature

/kind flake

What this PR does / why we need it:
The new --autopmaxprocs flag can be used to set the GOMAXPROCS environment variable to match the configured Linux container CPU quota.

Special notes for your reviewer:
The new --automaxprocs flag is disable by default. In the future it may be enabled by default, users would then pass --automaxprocs=false to disable it.

Does this PR introduce a user-facing change?:

Add a new `--automaxprocs` flag to set the `GOMAXPROCS` environment variable to match the configured Linux container CPU quota.

[k8s-ci-robot]

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[nixpanic]

/cc jsafrane