Fix remove_check_constraint with if_exists: true never removing any check constraint

It was never finding existing constraints, because `CheckConstraintDefinition` was
validating all options--including `if_exists`--matched.

activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb

@@ -1256,10 +1256,10 @@ def check_constraint_options(table_name, expression, options) # :nodoc:
       # The +expression+ parameter will be ignored if present. It can be helpful
       # to provide this in a migration's +change+ method so it can be reverted.
       # In that case, +expression+ will be used by #add_check_constraint.
-      def remove_check_constraint(table_name, expression = nil, **options)
+      def remove_check_constraint(table_name, expression = nil, if_exists: false, **options)
         return unless supports_check_constraints?
 
-        return if options[:if_exists] && !check_constraint_exists?(table_name, **options)
+        return if if_exists && !check_constraint_exists?(table_name, **options)
 
         chk_name_to_delete = check_constraint_for!(table_name, expression: expression, **options).name
 

activerecord/lib/active_record/connection_adapters/sqlite3/schema_statements.rb

@@ -102,8 +102,8 @@ def add_check_constraint(table_name, expression, **options)
           end
         end
 
-        def remove_check_constraint(table_name, expression = nil, **options)
-          return if options[:if_exists] && !check_constraint_exists?(table_name, **options)
+        def remove_check_constraint(table_name, expression = nil, if_exists: false, **options)
+          return if if_exists && !check_constraint_exists?(table_name, **options)
 
           check_constraints = check_constraints(table_name)
           chk_name_to_delete = check_constraint_for!(table_name, expression: expression, **options).name

activerecord/test/cases/migration/check_constraint_test.rb

@@ -259,7 +259,9 @@ def test_remove_check_constraint
         def test_removing_check_constraint_with_if_exists_option
           @connection.add_check_constraint :trades, "quantity > 0", name: "quantity_check"
 
-          @connection.remove_check_constraint :trades, name: "quantity_check"
+          assert_nothing_raised do
+            @connection.remove_check_constraint :trades, name: "quantity_check", if_exists: true
+          end
 
           error = assert_raises ArgumentError do
             @connection.remove_check_constraint :trades, name: "quantity_check"