Remove dead code related to an old symmetry feature.

[RyanJDick]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update
• Community Node Submission

Description

Remove dead code related to an old symmetry feature.

Note that postprocessing_settings was hard-coded to:

PostprocessingSettings(
    threshold=0.0,  # threshold,
    warmup=0.2,  # warmup,
    h_symmetry_time_pct=None,  # h_symmetry_time_pct,
    v_symmetry_time_pct=None,  # v_symmetry_time_pct,
)

This fixed configuration meant that the post-processing logic was having no effect.

QA Instructions, Screenshots, Recordings

I ran image generation with and without this change. The resultant images are identical.

Added/updated tests?

• Yes
• No: No tests affected.