Add more thorough log checks to see if the model server failed deployment during validation

[KaiyiLiu1234]

If the model server fails to access a model, it will produce a "failed to" log which is not picked up by the metal ci e2e. Resolve this by adding checks for failure.

[KaiyiLiu1234]

note: leverage model server exporter that will be implemented soon in the model server

[SamYuan1990]

we can use failure keywords. ref #288