Rename trace_filter field because it was broken

Before 9bccc2d649b8("Split packets in IPC-friendly-sized slices after
filtering"), setting a trace_filter could cause traced to crash.

Now the problem is fixed, but, in order to prevent a new configuration
(with a non-empty trace_filter) from crashing an old traced, this commit
renumbers the field.

Bug: 200028589
Change-Id: I9c0df14fa3690f2d47eb0eb36580631671d6fd46
diff --git a/CHANGELOG b/CHANGELOG
index 128093a..0861716 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -2,6 +2,10 @@
   Tracing service and probes:
     * Removed DCHECK that would cause crashes when a debug build of the service
       is used with a producer built with -DNDEBUG.
+    * Changed the service-side field-level filtering configuration protobuf
+      field number, because the feature had a bug. This is effectively
+      equivalent to deprecating the feature and reintroducing it under a
+      different name.
   Trace Processor:
     * Added reqiurement of separating queries by semi-colon (;) followed by
       new-line when specifying a query file with -q to trace processor shell.