Selecting a configuration value in Language Model is a noop for Copilot CLI

[DonJayamanne]

For Copilot CLI models: When I select xHigh or any other non-default value its a noop

Solution is replace as follows

			// Only create a new group if there's non-default config
-			const vendor = this.getVendors().find(v => v.vendor === metadata.vendor);
+			// Use _vendors directly instead of getVendors() which filters by `when` clause,
+			// because we need to store config for all vendors regardless of UI visibility.
+			const vendor = this._vendors.get(metadata.vendor);

However then we have duplicates as follows, and that also requires a change