policy.defaultValue confusion

[roblourens]

There are some policy.defaultValue which have a different value than the setting's normal default value, like the mcp one:

vscode/src/vs/workbench/contrib/chat/browser/chat.contribution.ts

Lines 240 to 245 in cc47994

	policy: {
	name: 'ChatMCP',
	minimumVersion: '1.99',
	previewFeature: true,
	defaultValue: false
	}

Is that on purpose? Why do we do that?

Also, I think you told me that policy.defaultValue only has an effect for previewFeature: true settings, is that true? Could you add some comments to IPolicy explaining more about how thsi works so we aren't guessing and copy/pasting?