[pulsar-server] add broker-configuration for relative dispatch thrott…

…ling (apache#5804)

### Motivation 
As we discussed at apache#5797, adding broker level relative dispatch-throttling-config.

conf/broker.conf

@@ -226,6 +226,11 @@ dispatchThrottlingRatePerReplicatorInMsg=0
 # Using a value of 0, is disabling replication message-byte dispatch-throttling
 dispatchThrottlingRatePerReplicatorInByte=0
 
+# Dispatch rate-limiting relative to publish rate. 
+# (Enabling flag will make broker to dynamically update dispatch-rate relatively to publish-rate: 
+# throttle-dispatch-rate = (publish-rate + configured dispatch-rate).
+dispatchThrottlingRateRelativeToPublishRate=false
+
 # By default we enable dispatch-throttling for both caught up consumers as well as consumers who have
 # backlog.
 dispatchThrottlingOnNonBacklogConsumerEnabled=true

conf/standalone.conf

@@ -169,6 +169,11 @@ dispatchThrottlingRatePerTopicInMsg=0
 # default message-byte dispatch-throttling
 dispatchThrottlingRatePerTopicInByte=0
 
+# Dispatch rate-limiting relative to publish rate. 
+# (Enabling flag will make broker to dynamically update dispatch-rate relatively to publish-rate: 
+# throttle-dispatch-rate = (publish-rate + configured dispatch-rate).
+dispatchThrottlingRateRelativeToPublishRate=false
+
 # By default we enable dispatch-throttling for both caught up consumers as well as consumers who have
 # backlog.
 dispatchThrottlingOnNonBacklogConsumerEnabled=true

pulsar-broker-common/src/main/java/org/apache/pulsar/broker/ServiceConfiguration.java

@@ -453,7 +453,13 @@ public class ServiceConfiguration implements PulsarConfiguration {
         doc = "Default number of message-bytes dispatching throttling-limit for every replicator in replication. \n\n"
             + "Using a value of 0, is disabling replication message-byte dispatch-throttling")
     private long dispatchThrottlingRatePerReplicatorInByte = 0;
-
+    @FieldContext(
+            dynamic = true,
+            category = CATEGORY_POLICIES,
+            doc = "Dispatch rate-limiting relative to publish rate. (Enabling flag will make broker to dynamically "
+                    + "update dispatch-rate relatively to publish-rate: "
+                    + "throttle-dispatch-rate = (publish-rate + configured dispatch-rate) ")
+    private boolean dispatchThrottlingRateRelativeToPublishRate = false;
     @FieldContext(
         dynamic = true,
         category = CATEGORY_POLICIES,

pulsar-broker/src/main/java/org/apache/pulsar/broker/service/persistent/DispatchRateLimiter.java

@@ -138,7 +138,8 @@ private DispatchRate createDispatchRate() {
                 dispatchThrottlingRateInByte = -1;
         }
 
-        return new DispatchRate(dispatchThrottlingRateInMsg, dispatchThrottlingRateInByte, 1);
+        return new DispatchRate(dispatchThrottlingRateInMsg, dispatchThrottlingRateInByte, 1,
+                config.isDispatchThrottlingRateRelativeToPublishRate());
     }
 
     /**