Issue placeholder deprecation warning only on initial component render

[adammcfadden]

🙋 Feature Request

#2759 + #2966 deprecated placeholders and usage of placeholders now outputs a console.warn message. The warning message is currently output on each render of the component, which can fill up the console pretty quickly.

This request is to make a change to the implementation so that the deprecation warning is only display on the initial render of the component. This pattern is currently implemented in the provider for a warning there.

🤔 Expected Behavior

One deprecation message is sent to console.warn when the component is rendered. Subsequent re-renders to not send another warning.

😯 Current Behavior

A deprecation message is sent to the console with every re-render of the component.

💁 Possible Solution

Implement the same pattern as the Provider for warning only once..

🔦 Context

Clutters the console with warnings, which can hide other warnings.

🧢 Your Company/Team

Adobe/Marketo

[adammcfadden]

Filled #3251 as a separate, but related issue. Filled as a different issue to allow for separate discussion/acceptance/rejection of the requests as they are different ways to tackle the issue.

[snowystinger]

This looks like a good change to make.