ISSUE 3044: ETCD tests hang. Added global timeout, fork tests jvm, fi…

…xed noop slf4j to see log in case of hang (#3051)

Descriptions of the changes in this PR:

### Motivation

ETCD test flake / hang occasionally causing CI job timeout.

### Changes

Added global timeout - kill test early if hanged
fork tests jvm - I think it helped locally (no repro) but possibly just reduced frequency of hangs 
fixed noop slf4j warning, also to see log in case of hang 

Master Issue: #3044

metadata-drivers/etcd/build.gradle

@@ -54,3 +54,6 @@ publishing {
     }
 }
 
+test {
+    forkEvery = 1
+}

metadata-drivers/etcd/src/test/java/org/apache/bookkeeper/metadata/etcd/testing/EtcdTestBase.java

@@ -31,13 +31,18 @@
 import org.junit.AfterClass;
 import org.junit.Before;
 import org.junit.BeforeClass;
+import org.junit.Rule;
+import org.junit.rules.Timeout;
 
 /**
  * A test base that setup etcd cluster for testing.
  */
 @Slf4j
 public abstract class EtcdTestBase {
 
+    @Rule
+    public Timeout globalTimeout = Timeout.seconds(120);
+
     protected static EtcdContainer etcdContainer;
 
     @BeforeClass