Create or update tenants with clusters that do not exist should not be allowed

[murong00]

Describe the bug
Currently, it is allowed to run pulsar-admin tenants with clusters that do not exist as below:

$ bin/pulsar-admin clusters list
pulsar-cluster-test
$ bin/pulsar-admin tenants list
public
$ bin/pulsar-admin tenants create test-tenant --admin-roles role1,role2 --allowed-clusters pulsar-cluster-test-11
$ bin/pulsar-admin tenants list
test-tenant
public

It is better to check that the cluster exists before operating tenants with it.