Fix fallback to RunHloModuleIterationLiterals.
Fix fallback to RunHloModuleIterationLiterals.

Trying to parse RunHloModuleLiterals may already add one iteration. So we need
to clear it before adding the RunHloModuleIterationLiterals proto.

FUTURE_COPYBARA_INTEGRATE_REVIEW=https://github.com/openxla/xla/pull/13639 from philipphack:u_layer_uaf_xla 91ebf7b4a2ac90ebadce27d1a73e88fb4513aed4
