logd: filters remove leading expire messages and rate

- Cleanup resulting from experience and feedback
- When filtering inside logd, drop any leading expire messages, they
  are cluttering up leading edge of tombstones (which filter by pid)
- Increase and introduce EXPIRE_RATELIMIT from 1 to 10 seconds
- Increase EXPIRE_THRESHOLD from 4 to 10 count
- Improve the expire messages from:
   logd : uid=1000(system) too chatty comm=com.google.android.phone,
                                                   expire 2800 lines
  change tag to be more descriptive, and reduce accusatory tone to:
   chatty : uid=1000(system) com.google.android.phone expire 2800
                                                               lines
- if the UID name forms a prefix for comm name, then drop UID name

Change-Id: Ied7cc04c0ab3ae02167649a0b97378e44ef7b588
diff --git a/logd/LogBufferElement.h b/logd/LogBufferElement.h
index 3dcf9d1..ca2c3a6 100644
--- a/logd/LogBufferElement.h
+++ b/logd/LogBufferElement.h
@@ -50,8 +50,9 @@
 
 #define EXPIRE_HOUR_THRESHOLD 24 // Only expire chatty UID logs to preserve
                                  // non-chatty UIDs less than this age in hours
-#define EXPIRE_THRESHOLD 4       // A smaller expire count is considered too
+#define EXPIRE_THRESHOLD 10      // A smaller expire count is considered too
                                  // chatty for the temporal expire messages
+#define EXPIRE_RATELIMIT 10      // maximum rate in seconds to report expiration
 
 class LogBufferElement {
     const log_id_t mLogId;