fix(large-video): make blurred background fit whole screen

css/_videolayout_default.scss

     top: 0;
     width: 100%;
 
-    &.fit-full-height #largeVideoBackground {
-        height: 100%;
-        width: auto;
-    }
-
-    .fit-full-width #largeVideoBackground {
-        height: auto;
-        width: 100%;
+    #largeVideoBackground {
+        min-height: 100%;
+        min-width: 100%;
     }
 }
 #largeVideoBackgroundContainer {

react/features/large-video/components/LargeVideoBackground.web.js

     PORTRAIT: 'portrait'
 };
 
-/**
- * A mapping of orientations to a class that should fit the
- * {@code LargeVideoBackground} into its container.
- *
- * @private
- * @type {Object}
- */
-const ORIENTATION_TO_CLASS = {
-    [ORIENTATION.LANDSCAPE]: 'fit-full-width',
-    [ORIENTATION.PORTRAIT]: 'fit-full-height'
-};
-
 /**
  * The type of the React {@code Component} props of
  * {@link LargeVideoBackgroundCanvas}.
         const {
             hidden,
             mirror,
-            orientationFit,
             showLocalProblemFilter,
             showRemoteProblemFilter
         } = this.props;
-        const orientationClass = orientationFit
-            ? ORIENTATION_TO_CLASS[orientationFit] : '';
         const classNames = `large-video-background ${mirror ? 'flip-x' : ''} ${
-            hidden ? 'invisible' : ''} ${orientationClass} ${
+            hidden ? 'invisible' : ''} ${
             showLocalProblemFilter ? 'videoProblemFilter' : ''} ${
             showRemoteProblemFilter ? 'remoteVideoProblemFilter' : ''}`;