Fix false positive readiness health check status in mpHealth, before application starts

[pgunapal]

When OpenLiberty server starts up, and the mpHealth endpoint (/health or /health/ready) becomes available before the application starts up, it will give a false positive health check status, as being healthy. It should indicate that the health status is DOWN, till the application is fully started.

[pgunapal]

• Create an out-of-the-box health check to determine if the application has started or not, for the /health/ready endpoint.
• Remove the out-of-the-box health check from the payload response, once the application has started.