Use appropriate config schema for the Display comment (display_comment) property

Problem/Motivation

Currently the Administrative comment section of the views is a textarea field (allowing multiline values), however the schema defines it as a label, which has a Regex constraint that control characters such as new lines are not allowed.

Steps to reproduce

Create a view and edit the Administrative comment with a piece of multiline text.

Then inspect the view using the config inspector UI, under the Validation error section, you should see the following:

Labels are not allowed to span multiple lines or contain control characters.

Proposed resolution

Switch the config schema type from label to text.

Remaining tasks

Provide MR.