BREAKING: drop .optional (#42734)

- it has been deprecated for a while, and we want to eventually have .optional() validators. Removing it will expose anyone who is depending on it, so they don't silently fail later thinking the truthy function means it's actually optional.

GitOrigin-RevId: 10dcb3d3689a136c634b25e0ab2fdd5967f8f305

Author: ianmacartney

src/values/validators.ts

@@ -39,10 +39,6 @@ abstract class BaseValidator<
     this.isOptional = isOptional;
     this.isConvexValidator = true;
   }
-  /** @deprecated - use isOptional instead */
-  get optional(): boolean {
-    return this.isOptional === "optional" ? true : false;
-  }
   /** @internal */
   abstract get json(): ValidatorJSON;
   /** @internal */