fix(seekbar): don't disable if live tracker's seekable is infinity (#5721)

This was done to make the behavior on Android with HLS live streams better but the it's opening us up to too many potential issues, like a user not being able to properly disable the control bar, that we should just back it out.

Author: gkatsev

src/js/control-bar/progress-control/seek-bar.js

@@ -115,12 +115,6 @@ class SeekBar extends Slider {
       duration = this.player_.liveTracker.liveCurrentTime();
     }
 
-    if (liveTracker && liveTracker.seekableEnd() === Infinity) {
-      this.disable();
-    } else {
-      this.enable();
-    }
-
     // machine readable value of progress bar (percentage complete)
     this.el_.setAttribute('aria-valuenow', (percent * 100).toFixed(2));