Tear down "legacy" DCR stack

[georgeblahblah]

Since spinning up dedicated stacks for different purposes in #9955 we should tear down the legacy stack:

dotcom-rendering/dotcom-rendering/cdk/bin/cdk.ts

Lines 14 to 29 in bb185ff

	new DotcomRendering(cdkApp, 'DotcomRendering-PROD', {
	...sharedProps,
	app: 'rendering',
	stage: 'PROD',
	minCapacity: 3,
	maxCapacity: 12,
	instanceType: 't4g.small',
	});
	new DotcomRendering(cdkApp, 'DotcomRendering-CODE', {
	...sharedProps,
	app: 'rendering',
	stage: 'CODE',
	minCapacity: 1,
	maxCapacity: 4,
	instanceType: 't4g.micro',
	});

This should be replaced with a new stack which handles miscellaneous requests like the email newsletters page.

This also handles AMP requests. We should redistribute these across the other stacks.