[bug][java-client] Client creation fails with enableTransactions=true if topic transaction_coordinator_assign has not been created yet

[nicoloboschi]

Describe the bug
Client creation fails with enableTransactions=true if topic transaction_coordinator_assign has not been created yet

Caused by: org.apache.pulsar.client.api.transaction.TransactionCoordinatorClientException: org.apache.pulsar.client.api.PulsarClientException$BrokerMetadataException: {"errorMsg":"Namespace not found","reqId":3642126209754600375, "remote":"localhost/127.0.0.1:54629", "local":"/127.0.0.1:54823"}
	at app//org.apache.pulsar.client.api.transaction.TransactionCoordinatorClientException.unwrap(TransactionCoordinatorClientException.java:131)
	at app//org.apache.pulsar.client.api.transaction.TransactionCoordinatorClientException.unwrap(TransactionCoordinatorClientException.java:129)
	at app//org.apache.pulsar.client.impl.transaction.TransactionCoordinatorClientImpl.start(TransactionCoordinatorClientImpl.java:70)
	at app//org.apache.pulsar.client.impl.PulsarClientImpl.<init>(PulsarClientImpl.java:204)
	... 47 more

I found this while enabling transactions on Pulsar standalone but it could apply also in a real cluster.

To Reproduce

• Start Pulsar standalone with transactions enabled (see this pull for reference
• Create a client suddenly after Pulsar is ready (but the topic doesn't exist yet)

Expected behavior
The client should work out of the box without throwing exceptions.
Perhaps an infinite backoff retry with severe logging could be a good solution.

Additional context
All the Pulsar versions

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