testclusters detect from settings that security is enabled
if a user is not specified using the DSL introduced in this PR, a default one is created
the appropriate wait conditions are used authenticating with the first user defined in the DSL ( or the default user ).
an example DSL to create a user is user username:"test_user" password:"x-pack-test-password" role: "superuser" all keys are optional and default to the values shown in this example
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