tests: Change seek test output to match test harness timing.

We are not interested in testing the timing of buffer loads (since that will vary based on hardware), we just need to know that we got a buffer load event.

Furthermore all our seeks are in-buffer so multiple buffer full events shouldn't happen in Ruffle.

tests/tests/swfs/avm1/netstream_seek_flv/output.txt

@@ -2,6 +2,10 @@ onStatus update
 level: status
 code: NetStream.Play.Start
 
+onStatus update
+level: status
+code: NetStream.Buffer.Full
+
 netStatusOnMetaData
 //ns.seek(0.5);
 onStatus update
@@ -19,7 +23,3 @@ undefined
 onStatus update
 level: status
 code: NetStream.Seek.Notify
-
-onStatus update
-level: status
-code: NetStream.Buffer.Full

tests/tests/swfs/avm2/netstream_seek_flv/output.txt

@@ -47,6 +47,3 @@ netStatus
 description: Seek Complete -1
 level: status
 code: NetStream.Seek.Complete
-netStatus
-code: NetStream.Buffer.Full
-level: status