clear core tap cache on formula creation

Addresses inability to find just-created formula, see https://github.com/Homebrew/brew/pull/19244#issuecomment-2646030394 for context.

Library/Homebrew/dev-cmd/create.rb

@@ -220,6 +220,7 @@ module Homebrew
         path = fc.write_formula!
 
         formula = Homebrew.with_no_api_env do
+          CoreTap.instance.clear_cache
           Formula[fc.name]
         end
         PyPI.update_python_resources! formula, ignore_non_pypi_packages: true if args.python?

Library/Homebrew/formula_creator.rb

@@ -100,9 +100,9 @@ module Homebrew
     sig { params(name: String).returns(String) }
     def latest_versioned_formula(name)
       name_prefix = "#{name}@"
-      Tap.fetch("homebrew/core").formula_names
-         .select { |f| f.start_with?(name_prefix) }
-         .max_by { |v| Gem::Version.new(v.sub(name_prefix, "")) } || "python"
+      CoreTap.instance.formula_names
+             .select { |f| f.start_with?(name_prefix) }
+             .max_by { |v| Gem::Version.new(v.sub(name_prefix, "")) } || "python"
     end
 
     sig { returns(String) }