Deprecate AnalyticsListener.onSeekStarted.

The new onPositionDiscontinuity callback contains sufficient information, so
that this former workaround to obtain the position before a seek is no longer
needed.

PiperOrigin-RevId: 365993937

library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsCollector.java

@@ -170,6 +170,7 @@ public class AnalyticsCollector
    * Notify analytics collector that a seek operation will start. Should be called before the player
    * adjusts its state and position to the seek.
    */
+  @SuppressWarnings("deprecation") // Calling deprecated listener method.
   public final void notifySeekStarted() {
     if (!isSeeking) {
       EventTime eventTime = generateCurrentPlayerMediaPeriodEventTime();

library/core/src/main/java/com/google/android/exoplayer2/analytics/AnalyticsListener.java

@@ -553,10 +553,11 @@ public interface AnalyticsListener {
       @DiscontinuityReason int reason) {}
 
   /**
-   * Called when a seek operation started.
-   *
-   * @param eventTime The event time.
+   * @deprecated Use {@link #onPositionDiscontinuity(EventTime, Player.PositionInfo,
+   *     Player.PositionInfo, int)} instead, listening to changes with {@link
+   *     Player#DISCONTINUITY_REASON_SEEK}.
    */
+  @Deprecated
   default void onSeekStarted(EventTime eventTime) {}
 
   /**