Update postfix.grok (skipped, still being delivered)

Pattern for the following logs added,
```Sep 19 11:38:52 XXX-stg postfix/qmgr[125238]: ED06590130AA1C9D6D862: skipped, still being delivered```

Author: Busindre

postfix.grok

@@ -51,6 +51,7 @@ POSTFIX_CLEANUP_PREPEND %{POSTFIX_QUEUEID:postfix_queueid}: prepend: %{POSTFIX_C
 POSTFIX_CLEANUP_MESSAGEID %{POSTFIX_QUEUEID:postfix_queueid}: message-id=<?%{GREEDYDATA_NO_BRACKET:postfix_message-id}>?
 
 # qmgr patterns
+POSTFIX_QMGR_SKIPPED %{POSTFIX_QUEUEID:postfix_queueid}: skipped, still being delivered
 POSTFIX_QMGR_REMOVED %{POSTFIX_QUEUEID:postfix_queueid}: removed
 POSTFIX_QMGR_ACTIVE %{POSTFIX_QUEUEID:postfix_queueid}: %{POSTFIX_KEYVALUE_DATA:postfix_keyvalue_data} \(queue active\)
 POSTFIX_QMGR_EXPIRED %{POSTFIX_QUEUEID:postfix_queueid}: from=<%{DATA:postfix_from}>, status=%{STATUS_WORD:postfix_status}, returned to sender
@@ -116,7 +117,7 @@ POSTFIX_SCACHE_TIMESTAMP statistics: start interval %{SYSLOGTIMESTAMP:postfix_sc
 # aggregate all patterns
 POSTFIX_SMTPD %{POSTFIX_SMTPD_CONNECT}|%{POSTFIX_SMTPD_DISCONNECT}|%{POSTFIX_SMTPD_LOSTCONN}|%{POSTFIX_SMTPD_NOQUEUE}|%{POSTFIX_SMTPD_PIPELINING}|%{POSTFIX_TLSCONN}|%{POSTFIX_WARNING}|%{POSTFIX_SMTPD_PROXY}|%{POSTFIX_KEYVALUE}
 POSTFIX_CLEANUP %{POSTFIX_CLEANUP_MESSAGEID}|%{POSTFIX_CLEANUP_MILTER}|%{POSTFIX_CLEANUP_PREPEND}|%{POSTFIX_WARNING}|%{POSTFIX_KEYVALUE}
-POSTFIX_QMGR %{POSTFIX_QMGR_REMOVED}|%{POSTFIX_QMGR_ACTIVE}|%{POSTFIX_QMGR_EXPIRED}|%{POSTFIX_WARNING}
+POSTFIX_QMGR %{POSTFIX_QMGR_REMOVED}|%{POSTFIX_QMGR_ACTIVE}|%{POSTFIX_QMGR_EXPIRED}|%{POSTFIX_WARNING}|%{POSTFIX_QMGR_SKIPPED}
 POSTFIX_PIPE %{POSTFIX_PIPE_ANY}
 POSTFIX_POSTSCREEN %{POSTFIX_PS_CONNECT}|%{POSTFIX_PS_ACCESS}|%{POSTFIX_PS_NOQUEUE}|%{POSTFIX_PS_TOOBUSY}|%{POSTFIX_PS_CACHE}|%{POSTFIX_PS_DNSBL}|%{POSTFIX_PS_VIOLATIONS}|%{POSTFIX_WARNING}
 POSTFIX_DNSBLOG %{POSTFIX_DNSBLOG_LISTING}|%{POSTFIX_WARNING}