Clean up NOP constructor lines in RTP readers

PiperOrigin-RevId: 465067191
(cherry picked from commit ed60c885)

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/reader/RtpMpeg4Reader.java

@@ -62,7 +62,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     this.payloadFormat = payloadFormat;
     firstReceivedTimestamp = C.TIME_UNSET;
     previousSequenceNumber = C.INDEX_UNSET;
-    sampleLength = 0;
   }
 
   @Override

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/reader/RtpVp8Reader.java

@@ -74,9 +74,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     fragmentedSampleTimeUs = C.TIME_UNSET;
     // The start time offset must be 0 until the first seek.
     startTimeOffsetUs = 0;
-    gotFirstPacketOfVp8Frame = false;
-    isKeyFrame = false;
-    isOutputFormatSet = false;
   }
 
   @Override

libraries/exoplayer_rtsp/src/main/java/androidx/media3/exoplayer/rtsp/reader/RtpVp9Reader.java

@@ -81,10 +81,6 @@ import org.checkerframework.checker.nullness.qual.MonotonicNonNull;
     previousSequenceNumber = C.INDEX_UNSET;
     width = C.LENGTH_UNSET;
     height = C.LENGTH_UNSET;
-    // TODO(b/240318842) Clean up VP8/VP9 reader.
-    gotFirstPacketOfVp9Frame = false;
-    reportedOutputFormat = false;
-    isKeyFrame = false;
   }
 
   @Override