React 19: any custom prop type validation needs to be refactored

[matthewgallo]

We have prop type utilities, such as PropTypes.string.isRequired.if(() => ....),, to handle a certain prop being conditionally required. With the removal of prop-types support in React 19, these utilities need to be refactored to handle the validation differently.

• UserAvatar
• UserProfileImage
• APIKeyDownloader
• GuideBanner
• isRequiredIf
• deprecateProp
• deprecatePropUsage
• AboutModal
• CreateModal
• EditTearsheet
• EmptyState
• ActionSet
• Datagrid
• TearsheetNarrow
• Tearsheet
• SidePanel
• PageHeader

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Thinking more about this, I'm starting to feel that we don't need to migrate all of these components to use custom prop validation. React 19 leans on the fact that TypeScript is now the way to enforce type checking, I think we should as well. This means that we remove any tests expecting console errors from the custom validations we've added in the past since anything prop-type related is now silently ignored.