refactor(material/slider): remove explicit change detection

Now that `OnPush` is the default, we can remove it from the metadata.

Author: crisbeto

src/material/slider/slider-thumb.ts

@@ -8,7 +8,6 @@
 
 import {
   AfterViewInit,
-  ChangeDetectionStrategy,
   ChangeDetectorRef,
   Component,
   ElementRef,
@@ -45,7 +44,6 @@ import {Platform} from '@angular/cdk/platform';
   host: {
     'class': 'mdc-slider__thumb mat-mdc-slider-visual-thumb',
   },
-  changeDetection: ChangeDetectionStrategy.OnPush,
   encapsulation: ViewEncapsulation.None,
   providers: [{provide: MAT_SLIDER_VISUAL_THUMB, useExisting: MatSliderVisualThumb}],
   imports: [MatRipple],

src/material/slider/slider.ts

@@ -12,7 +12,6 @@ import {
   afterRenderEffect,
   AfterViewInit,
   booleanAttribute,
-  ChangeDetectionStrategy,
   ChangeDetectorRef,
   Component,
   computed,
@@ -74,7 +73,6 @@ import {_CdkPrivateStyleLoader} from '@angular/cdk/private';
     '[class._mat-animation-noopable]': '_noopAnimations',
   },
   exportAs: 'matSlider',
-  changeDetection: ChangeDetectionStrategy.OnPush,
   encapsulation: ViewEncapsulation.None,
   providers: [{provide: MAT_SLIDER, useExisting: MatSlider}],
   imports: [MatSliderVisualThumb],