fix: Avoid clear buffer when select the same audio track (#6959)

lib/player.js

@@ -4735,9 +4735,9 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
                 Math.abs((a.video.width || 0) - (b.video.width || 0));
         }
       };
-        // Find the variant whose size is closest to the active variant.  This
-        // ensures we stay at about the same resolution when just changing the
-        // language/role.
+      // Find the variant whose size is closest to the active variant.  This
+      // ensures we stay at about the same resolution when just changing the
+      // language/role.
       const active = this.streamingEngine_.getCurrentVariant();
       const set =
             this.currentAdaptationSetCriteria_.create(this.manifest_.variants);
@@ -4748,6 +4748,10 @@ shaka.Player = class extends shaka.util.FakeEventTarget {
           bestVariant = curVariant;
         }
       }
+      if (bestVariant == active) {
+        shaka.log.debug('Audio already selected.');
+        return;
+      }
       if (bestVariant) {
         const track = shaka.util.StreamUtils.variantToTrack(bestVariant);
         this.selectVariantTrack(track, /* clearBuffer= */ true, safeMargin);