Don't apply default colors in the colors plugin when defaults are used

[LeeLenaleee]

Resolves: #11914

[SteveByerly]

Note that this fix relies on matching the string values being used on the Default class ctor in core/defaults.

This runs the risk of breaking if those strings ever change, even if the color values do not change, for example if spaces were added 'rgba(0, 0, 0, 0.1)'.

Chart.js/src/core/core.defaults.js

Lines 38 to 42 in 79773b7

	export class Defaults {
	constructor(_descriptors, _appliers) {
	this.animation = undefined;
	this.backgroundColor = 'rgba(0,0,0,0.1)';
	this.borderColor = 'rgba(0,0,0,0.1)';

[LeeLenaleee]

I don't think that those values or formatting will change. And if it will change the test will break, so you need to revert it or update the colors plugin.

So this should never break this fix unless the test is removed