[feature] Make it easier to run the api server locally

[anishasthana]

Feature Area

/area backend

Running the API server locally is currently challenging as it creates a k8sclient. Allowing for specification of an SA token will make things much easier.

More context from an issue created by @HumairAK (#10993)

When the backend Pipeline server initiates clients, it uses InClusterConfig to create the k8s client, this is annoying because it makes running the api server locally a non option (unless you mock the SA token paths). Simply parameterizing the config to allow for SA token would resolve this.

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