Improve readiness image to allow for shorter check intervals

- introduce interval parameter that can be passed to define check interval
- reduce default wait intervals from between 5-11 to 2-6 seconds
- move checks to separate methods [0]

[0] this prepares executing the checks in parallel in another change once this
one should work fine

Issue-ID: INT-2284
Change-Id: Ie93360e700b3d1898bed51c0612e5430d7d502cc
Signed-off-by: Fiete Ostkamp <Fiete.Ostkamp@telekom.de>
2 files changed