[fix][ci][branch-3.0] Increase Maven's heap size from 1024m to 1500m as it is in master

Author: lhotari

.github/workflows/pulsar-ci-flaky.yaml

@@ -37,7 +37,7 @@ concurrency:
   cancel-in-progress: true
 
 env:
-  MAVEN_OPTS: -Xss1500k -Xmx1024m -Daether.connector.http.reuseConnections=false -Daether.connector.requestTimeout=60000 -Dhttp.keepAlive=false -Dmaven.wagon.http.pool=false -Dmaven.wagon.http.retryHandler.class=standard -Dmaven.wagon.http.retryHandler.count=3 -Dmaven.wagon.http.retryHandler.requestSentEnabled=true -Dmaven.wagon.http.serviceUnavailableRetryStrategy.class=standard -Dmaven.wagon.rto=60000
+  MAVEN_OPTS: -Xss1500k -Xmx1500m -Daether.connector.http.reuseConnections=false -Daether.connector.requestTimeout=60000 -Dhttp.keepAlive=false -Dmaven.wagon.http.pool=false -Dmaven.wagon.http.retryHandler.class=standard -Dmaven.wagon.http.retryHandler.count=3 -Dmaven.wagon.http.retryHandler.requestSentEnabled=true -Dmaven.wagon.http.serviceUnavailableRetryStrategy.class=standard -Dmaven.wagon.rto=60000
   # defines the retention period for the intermediate build artifacts needed for rerunning a failed build job
   # it's possible to rerun individual failed jobs when the build artifacts are available
   # if the artifacts have already been expired, the complete workflow can be rerun by closing and reopening the PR or by rebasing the PR