[feature] KEP-11385: Implement end-to-end testing for validating and processing literal inputs

[mprahl]

Feature Area

/area backend

Part of KEP-11385.

Acceptance Criteria

Implement end-to-end testing for the valid and invalid test cases corresponding to the Execute Pipeline E2E and API Server: Verify Pipeline Run columns in KEP-11385.

[AggarwalKashvi]

Hello! I would like to work on this

[alyssacgoins]

Hey @AggarwalKashvi this issue is dependent on #12601, #12602 and #12603 being completed and merged in. Once those are in, the end-to-end testing for this feature can be added.