fix: Fix volume size validation

[jonathan-innis]

Fixes #6055

Description

This fixes the volume size string validation that should have already been performed to ensure that the resource value must be one of T, Ti, G, or Gi. You could bypass this check by specifying an integer; however, etcd would store this value as a string somewhere down the line which would cause us to fail to delete the EC2NodeClass.

There's an open issue against controller-gen to try and dig deeper into what causes the integer to be able to circumvent this validation but then pass through the validation later, causing it to fail.

How was this change tested?

make presubmit

Does this change impact docs?

• Yes, PR includes docs updates
• Yes, issue opened: #
• No

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

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[coveralls]

Pull Request Test Coverage Report for Build 8776080220

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.02%) to 81.963%

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Files with Coverage Reduction	New Missed Lines	%
pkg/providers/amifamily/ami.go	1	90.32%

Totals
Change from base Build 8769944868:	-0.02%
Covered Lines:	5394
Relevant Lines:	6581

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💛 - Coveralls

[jigisha620]

LGTM