[serve][bugfix] Clip number of retries shown in error message

[akyang-anyscale]

Why are these changes needed?

The status message should never display that serve will retry a "negative" amount of times. This can happen if the retry counter is larger than the failed threshold. If this is the case, just clip the lower bound to be 0 to avoid the confusing status message.

Related issue number

N/A

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