Migration of tests to VertxTestBase stateless mode

[vietj]

Motivation:

Migrate existing usage of VertxTestBase to stateless assertions.

An usage is typically migrated with:

1. Switch the test to stateless mode
2. Run the test, it will log incorrect usage of AsyncTestBase assertions which cannot reliably fail the test
3. Fix the incorrect unreliable assertions, make sure that those assertions are called from a thread capable of doing so
4. Migrate the test from AsyncTestBase assertion usage and instead static asserts such as JUnit or AssertJ (this can be achieved by an agent)

This covers a portion of the (large) vertx test base.