KAFKA-15052 Fix the flaky testBalancePartitionLeaders - part II (#13908)

A follow-up to https://github.com/apache/kafka/pull/13804.
This follow-up adds the alternative fix approach mentioned in
the PR above - bumping the session timeout used in the test
with 1 second.

Reproducing the flake-out locally has been much harder than
on the CI runs, as neither Gradle with Java 11 or Java 14 nor
IntelliJ with Java 14 could show it, but IntelliJ with Java 11
could occasionally reproduce the failure the first time
immediately after a rebuild. While I was unable to see the
failure with the bumped session timeout, the testing procedure
definitely didn't provide sufficient reassurance for the
fix as even without it often I'd see hundreds of consecutive
successful test runs when the first run didn't fail.

Reviewers: Luke Chen <showuon@gmail.com>, Christo Lolov <lolovc@amazon.com>

metadata/src/test/java/org/apache/kafka/controller/QuorumControllerTest.java

@@ -334,7 +334,7 @@ public class QuorumControllerTest {
         List<Integer> brokersToFence = Collections.singletonList(3);
         short replicationFactor = (short) allBrokers.size();
         short numberOfPartitions = (short) allBrokers.size();
-        long sessionTimeoutMillis = 1000;
+        long sessionTimeoutMillis = 2000;
         long leaderImbalanceCheckIntervalNs = 1_000_000_000;
 
         try (