Major Description
PR introduce a concurrentTable creation that fails: https://github.com/linagora/james-project/pull/2139
```
java.util.concurrent.ExecutionException: java.lang.RuntimeException: java.lang.RuntimeException: com.datastax.driver.core.exceptions.ServerError: An unexpected error occurred server side on localhost/127.0.0.1:32818: java.lang.RuntimeException: java.util.concurrent.ExecutionException: org.apache.cassandra.exceptions.ConfigurationException: Column family ID mismatch (found b0736470-22b8-11e9-b4fb-f58bd8d3766a; expected b07168a0-22b8-11e9-b4fb-f58bd8d3766a)
at java.util.concurrent.FutureTask.report(FutureTask.java:122)
at java.util.concurrent.FutureTask.get(FutureTask.java:192)
at org.apache.james.util.concurrency.ConcurrentTestRunner.assertNoException(ConcurrentTestRunner.java:160)
at org.apache.james.util.concurrency.ConcurrentTestRunner.runSuccessfullyWithin(ConcurrentTestRunner.java:177)
at org.apache.james.util.concurrency.ConcurrentTestRunner$Builder.runSuccessfullyWithin(ConcurrentTestRunner.java:83)
at org.apache.james.backends.cassandra.init.CassandraTableManagerConcurrentTest.initializeTableShouldCreateAllTheTables(CassandraTableManagerConcurrentTest.java:61)
```
The 2 connections do not succeed to synchronize themselves upon table creation, leading to an invalid state...
We need to ensure that when we start james server concurrently, everything go smooth.
Table creation synchorinsation seems hard. Does this mean we need to externalize table creation, that would be needed to be run prior running James servers?