CAMEL-17948: Force waiting before checking the asserts of the mock

[essobedo]

Fix for https://issues.apache.org/jira/browse/CAMEL-17948

Motivation

While working on CAMEL-17945, I realized that the tests with the scope PER_CLASS leveraging the MockEndpoint to define their assertions can fail randomly because of a race condition issue. Indeed, with the current code, a message of a previous test method can potentially call the method countDown on the latch of the following test method causing unexpected behavior.

Modifications:

• When at least one message is expected, always wait until the latch is released to prevent conflicts of messages of different test methods
• Convert the counter to an AtomicInteger to guarantee the rest of an increment
• Use a fixed value of the counter when getting the Processor to avoid potential race condition issues between 2 successive accesses
• Add the new method expectedNoHeaderReceived to check if the received message has no headers (not related to the initial issue but needed for CAMEL-17945)
• Add the new method assertFalse to check if a given predicate is false (not related to the initial issue but needed for CAMEL-17945)

[github-actions]

⚠️ This PR changes Camel components and will be tested automatically.

[github-actions]

✔️ Finished component verification: 0 component(s) test failed out of 2 component(s) tested

[github-actions]

There are too many components to be tested in this PR, components were removed or the code needs a rebase: (22 likely to be tested)

[github-actions]

There are too many components to be tested in this PR, components were removed or the code needs a rebase: (22 likely to be tested)