Route against-direction objective constraints to outcome constraints in MOO

[saitcakmak]

Summary:
D109061377 relaxed MultiObjectiveOptimizationConfig validation so that, in multi-objective optimization, an outcome constraint can be placed on an objective metric (e.g. flops >= 42 while minimizing flops) to bound the objective against its optimization direction. Objective.get_unconstrainable_metric_names() now returns [] for MOO.

However, optimization_config_from_string (used by Client.configure_optimization) was never updated. It unconditionally converted any single-metric constraint on an objective metric into an objective threshold. Objective thresholds can only bound in the direction of optimization, so a constraint like flops >= 42.50 while minimizing flops was turned into an invalid threshold and tripped check_objective_thresholds_match_objectives:

UserInputError: Objective threshold on flops bounds from below but flops is being minimized.

This diff fixes the conversion so a single-metric constraint on an objective metric becomes an objective threshold only when it bounds the objective in its optimization direction (upper bound on a minimized objective, lower bound on a maximized one). A constraint that bounds against the optimization direction is kept as a true outcome constraint, which MOO now supports.

For objective="-flops, -train_ne" with ["flops >= 42.50", "flops <= 94.38", "train_ne <= 0.62938"]:

• flops >= 42.50 -> outcome constraint (against the minimize direction)
• flops <= 94.38 -> objective threshold (aligned with minimize)
• train_ne <= 0.62938 -> objective threshold (aligned with minimize)

Differential Revision: D109856433

[meta-codesync]

@saitcakmak has exported this pull request. If you are a Meta employee, you can view the originating Diff in D109856433.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.57%. Comparing base (025d7e5) to head (fe8702e).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5239   +/-   ##
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  Coverage   96.56%   96.57%           
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  Files         619      619           
  Lines       70273    70282    +9     
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+ Hits        67861    67875   +14     
+ Misses       2412     2407    -5     

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