Remove RCTGetMultiplierForContentSizeCategory (#39617)

Summary:
It seems this method is not referenced by anything anymore. I think #35017 made it redundant. Let's remove it?
I can also do the whole "Deprecate for one version, remove in the next" since this was publicly exported.

## Changelog:
[iOS] [REMOVED] - Remove RCTGetMultiplierForContentSizeCategory

Pull Request resolved: #39617

Test Plan: CI should pass

Reviewed By: dmytrorykun

Differential Revision: D49618166

Pulled By: cipolleschi

fbshipit-source-id: fb72e961d2a1eb9977944fea3ee4deeab46b946b

packages/react-native/React/UIUtils/RCTUIUtils.h

@@ -23,10 +23,6 @@ typedef struct {
 } RCTDimensions;
 extern __attribute__((visibility("default"))) RCTDimensions RCTGetDimensions(CGFloat fontScale);
 
-// Get font size multiplier for font base size (Large) by content size category
-extern __attribute__((visibility("default"))) CGFloat RCTGetMultiplierForContentSizeCategory(
-    UIContentSizeCategory category) __deprecated;
-
 #ifdef __cplusplus
 }
 #endif

packages/react-native/React/UIUtils/RCTUIUtils.m

@@ -29,28 +29,3 @@ RCTDimensions RCTGetDimensions(CGFloat fontScale)
 
   return result;
 }
-
-CGFloat RCTGetMultiplierForContentSizeCategory(UIContentSizeCategory category)
-{
-  static NSDictionary<NSString *, NSNumber *> *multipliers = nil;
-  static dispatch_once_t token;
-  dispatch_once(&token, ^{
-    multipliers = @{
-      UIContentSizeCategoryExtraSmall : @0.823,
-      UIContentSizeCategorySmall : @0.882,
-      UIContentSizeCategoryMedium : @0.941,
-      UIContentSizeCategoryLarge : @1.0,
-      UIContentSizeCategoryExtraLarge : @1.118,
-      UIContentSizeCategoryExtraExtraLarge : @1.235,
-      UIContentSizeCategoryExtraExtraExtraLarge : @1.353,
-      UIContentSizeCategoryAccessibilityMedium : @1.786,
-      UIContentSizeCategoryAccessibilityLarge : @2.143,
-      UIContentSizeCategoryAccessibilityExtraLarge : @2.643,
-      UIContentSizeCategoryAccessibilityExtraExtraLarge : @3.143,
-      UIContentSizeCategoryAccessibilityExtraExtraExtraLarge : @3.571
-    };
-  });
-
-  double value = multipliers[category].doubleValue;
-  return value > 0.0 ? value : 1.0;
-}