Fix callback tensor inputs that are never bound in the denoising loop (#14416)

Drop callback tensor inputs that are never bound in the denoising loop

LEditsPPPipelineStableDiffusion allows prompt_embeds, LEditsPPPipelineStableDiffusionXL
allows negative_add_time_ids and StableDiffusionXLControlNetUnionInpaintPipeline allows
masked_image_latents, but none of those names exist as locals in the respective __call__,
so callback_kwargs[k] = locals()[k] raises KeyError as soon as a user requests them.

Add a test_callback_inputs fast test to both LEdits++ test classes, which are plain
unittest.TestCase and therefore never ran the PipelineTesterMixin callback tests.

Co-authored-by: dg845 <58458699+dg845@users.noreply.github.com>