[fix] Fix incorrect unit and doc for `loadBalancerReportUpdateMaxInte…

…rvalMinutes` (apache#21448)

### Motivation
The documentation inaccurately represents the unit for loadBalancerReportUpdateMaxIntervalMinutes - it is actually in minutes, not seconds. Additionally, the explanation for loadBalancerBrokerLoadDataTTLInSeconds is unclear.
```
"The current default is loadBalancerReportUpdateMaxIntervalMinutes * 2. "
```
Actually, it numerically equates to loadBalancerReportUpdateMaxIntervalMinutes * 120.

### Modifications
- Correct the documentation

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

@@ -2243,7 +2243,7 @@ The delayed message index time step(in seconds) in per bucket snapshot segment,
     @FieldContext(
             category = CATEGORY_LOAD_BALANCER,
             dynamic = true,
-            doc = "Min delay of load report to collect, in milli-seconds"
+            doc = "Min delay of load report to collect, in minutes"
     )
     private int loadBalancerReportUpdateMaxIntervalMinutes = 15;
     @FieldContext(
@@ -2594,7 +2594,8 @@ The delayed message index time step(in seconds) in per bucket snapshot segment,
                     + "The logic tries to avoid (possibly unavailable) brokers with out-dated load data, "
                     + "and those brokers will be ignored in the load computation. "
                     + "When tuning this value, please consider loadBalancerReportUpdateMaxIntervalMinutes. "
-                    + "The current default is loadBalancerReportUpdateMaxIntervalMinutes * 2. "
+                    + "The current default value is loadBalancerReportUpdateMaxIntervalMinutes * 120, reflecting "
+                    + "twice the duration in seconds. "
                     + "(only used in load balancer extension TransferSheddeer)"
     )
     private long loadBalancerBrokerLoadDataTTLInSeconds = 1800;