make integration tests less flaky

[Tantalor93]

Name of feature:

make the integration tests less flaky on checking the health of running step-ca instance

Pain or issue this feature alleviates:

Why is this important to the project (if not answered above):

it sometimes happens that the server is not started before checking the health of the running server, this is caused by starting the server in a separate goroutine and there is no synchronization before testing the health of the server, it usually passes due to race condition

Is there documentation on how to use this feature? If so, where?

no

In what environments or workflows is this feature supported?

In what environments or workflows is this feature explicitly NOT supported (if any)?

Supporting links/other PRs/issues:

💔Thank you!

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