Remove tf_keras' TensorRT export test

This change doesn't affect OSS becuase this test was never available in OSS.

PiperOrigin-RevId: 615826673

Fix the error handling for pydot installation check. (#763)

`pydot.InvocationException` is only in `pydot_ng` and not in the `pydot` library.

PiperOrigin-RevId: 613787427

Implement auto-assignment for newly created issues.

PiperOrigin-RevId: 580745663