refactor(material/datepicker): update comparisonDateLabel value

Updates previous fix to remove - for Ids in calendar-body.ts and
revises comparisonDateLabel value to be Comparison range as
recommended.

Fixes b/195600299

src/material/datepicker/calendar-body.ts

@@ -464,7 +464,7 @@ export class MatCalendarBody<D = any> implements OnChanges, OnDestroy, AfterView
 
     if (this.comparisonStart !== null && this.comparisonEnd !== null) {
       if (value === this.comparisonStart && value === this.comparisonEnd) {
-        return `${this._comparisonStartLabelId}-${this._comparisonEndLabelId}`;
+        return `${this._comparisonStartLabelId} ${this._comparisonEndLabelId}`;
       } else if (value === this.comparisonStart) {
         return this._comparisonStartLabelId;
       } else if (value === this.comparisonEnd) {

src/material/datepicker/datepicker-intl.ts

@@ -69,7 +69,7 @@ export class MatDatepickerIntl {
    * A label used to indicate that the date is part of a selected comparison
    * sub range of dates (used by screen readers).
    */
-  comparisonDateLabel = 'Sub range';
+  comparisonDateLabel = 'Comparison range';
 
   /** Formats a range of years (used for visuals). */
   formatYearRange(start: string, end: string): string {