Remove not existing FluentdQueueLengthBurst alert

FluentdQueueLengthBurst alert has been removed as of Cluster Logging v5.1. Remove not existing alert for suppressing confusion.
Reference: https://bugzilla.redhat.com/show_bug.cgi?id=2083421

Author: bysnupy

modules/cluster-logging-collector-alerts.adoc

@@ -23,11 +23,6 @@ The following alerts are generated by the logging collector. You can view these
 |Fluentd is reporting that Prometheus could not scrape a specific Fluentd instance.
 |Critical
 
-|`FluentdQueueLengthBurst`
-|`In the last minute, fluentd <instance> buffer queue length increased more than 32. Current value is <value>.`
-|Fluentd is reporting that it cannot keep up with the data being indexed.
-|Warning
-
 |`FluentdQueueLengthIncreasing`
 |`In the last 12h, fluentd <instance> buffer queue length constantly increased more than 1. Current value is <value>.`
 |Fluentd is reporting that the queue size is increasing.