Consider increasing frequency of app host health checks update during startup

[DamianEdwards]

As the number of resources using WaitFor increases in an app project in such a way that a longer sequential "wait-for chain" is build up, the impact of the accumulated downtime between health checks updates increases.

For example, the Aspire Shop sample was updated for Aspire 9 to use WaitFor for four resources, that results in the following wait-for chains:

flowchart LR
    B[basketService] -->| waits for | C[baksetCache]
    F[frontend] -->| waits for | D[catalogService] -->| waits for | E[catalogDbManager] -->| waits for | G[catalogDb]

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If the update frequency for app host health checks is 1 second, then the longer chain shown above could result in up to 3 extra seconds of startup time.

We should consider increasing the frequency of health check updates during startup to something much tighter to minimize the impact of longer wait-for chains.

/Cc @mitchdenny