ISSUE #2073: ReadOnlyBookieTest#testBookieContinueWritingIfMulti…

…pleLedgersPresent is flaky

Descriptions of the changes in this PR:

Updated the test to use random port number for bookie startup instead of predefined one.

### Motivation

ReadOnlyBookieTest#testBookieContinueWritingIfMultipleLedgersPresent test is flaky due to this reason.

### Changes

(Describe: what changes you have made)

Master Issue: #2073 




Reviewers: Enrico Olivelli <eolivelli@gmail.com>, Sijie Guo <sijie@apache.org>

This closes #2074 from karanmehta93/master, closes #2073
diff --git a/bookkeeper-server/src/test/java/org/apache/bookkeeper/test/ReadOnlyBookieTest.java b/bookkeeper-server/src/test/java/org/apache/bookkeeper/test/ReadOnlyBookieTest.java
index 35b2fd3..329779c 100644
--- a/bookkeeper-server/src/test/java/org/apache/bookkeeper/test/ReadOnlyBookieTest.java
+++ b/bookkeeper-server/src/test/java/org/apache/bookkeeper/test/ReadOnlyBookieTest.java
@@ -245,7 +245,7 @@
         }
 
         ServerConfiguration newConf = newServerConfiguration(
-                conf.getBookiePort() + 1,
+                PortManager.nextFreePort(),
                 ledgerDirs[0], ledgerDirs);
         bsConfs.add(newConf);
         bs.add(startBookie(newConf));