fate: Don't use depreceated keepside option

The tests for concat use this option which is scheduled for removal and
does nothing any more. So remove it; otherwise, these tests would fail
at the next major version bump.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
Signed-off-by: James Almer <jamrial@gmail.com>

tests/fate-run.sh

@@ -471,10 +471,10 @@ concat(){
     awk "{gsub(/%SRCFILE%/, \"$sample\"); print}" $template > $concatfile
 
     if [ "$mode" = "md5" ]; then
-        run ffprobe${PROGSUF}${EXECSUF} -bitexact -show_streams -show_packets -v 0 -fflags keepside -safe 0 $extra_args $(target_path $concatfile) | tr -d '\r' > $packetfile
+        run ffprobe${PROGSUF}${EXECSUF} -bitexact -show_streams -show_packets -v 0 -safe 0 $extra_args $(target_path $concatfile) | tr -d '\r' > $packetfile
         do_md5sum $packetfile
     else
-        run ffprobe${PROGSUF}${EXECSUF} -bitexact -show_streams -show_packets -v 0 -of compact=p=0:nk=1 -fflags keepside -safe 0 $extra_args $(target_path $concatfile)
+        run ffprobe${PROGSUF}${EXECSUF} -bitexact -show_streams -show_packets -v 0 -of compact=p=0:nk=1 -safe 0 $extra_args $(target_path $concatfile)
     fi
 }