[perf] lua,ast_pipeline - combine a filter to reduce number of passes

[cscheid]

normalize-3 was among our slowest filters on main. This PR rewrites the post-processing of FloatRefTargets so that the work done in that filter happens inside normalize-2. Our A/B tester shows statistically significant improvement:

{'outcome': 'significant', 'winner': 'B', 'p_value': np.float64(5.343099192664396e-05), 'total_samples': 20, 'alpha_spent': 0.05, 'statistics': {'counts': {'A': 10, 'B': 10}, 'means': {'A': 0.7966938972473144, 'B': 0.7741650581359864}, 'variances': {'A': 7.135757199649984e-05, 'B': 9.23875652483197e-05}}}
Statistical Summary:
===================
Variant     Count         Mean      Std Dev
-------- -------- ------------ ------------
A              10     0.796694     0.008447
B              10     0.774165     0.009612