fix: Use getSegmentAvailabilityStart instead of getSeekRangeStart to evict segments (#7867)

Author: avelad

lib/dash/dash_parser.js

@@ -695,10 +695,11 @@ shaka.dash.DashParser = class {
       // that the complex logic of multi-Period eviction and period-flattening
       // is correct.  See also:
       // https://github.com/shaka-project/shaka-player/issues/3169#issuecomment-823580634
+      const availabilityStart =
+          presentationTimeline.getSegmentAvailabilityStart();
       for (const stream of Object.values(this.streamMap_)) {
         if (stream.segmentIndex) {
-          stream.segmentIndex.evict(
-              presentationTimeline.getSegmentAvailabilityStart());
+          stream.segmentIndex.evict(availabilityStart);
         }
       }
     } else {

lib/media/streaming_engine.js

@@ -2344,7 +2344,7 @@ shaka.media.StreamingEngine = class {
     const segmentIndex = mediaState.stream.segmentIndex;
     if (segmentIndex instanceof shaka.media.MetaSegmentIndex) {
       segmentIndex.evict(
-          this.manifest_.presentationTimeline.getSeekRangeStart());
+          this.manifest_.presentationTimeline.getSegmentAvailabilityStart());
     }
 
     const logPrefix = shaka.media.StreamingEngine.logPrefix_(mediaState);