Tests: Drop unnecessary frontend flags in ModuleInterface/lazy-typecheck.swift

The `-experimental-skip-all-function-bodies` and
`-experimental-serialize-external-decls-only` flags are unnecessary because
this test now uses the `-typecheck` action instead of the `-emit-module`
action.

Author: tshortli

test/ModuleInterface/lazy-typecheck.swift

@@ -1,6 +1,6 @@
 // RUN: %empty-directory(%t)
 
-// RUN: %target-swift-frontend -swift-version 5 %S/../Inputs/lazy_typecheck.swift -module-name lazy_typecheck -typecheck -emit-module-interface-path %t/lazy_typecheck.swiftinterface -enable-library-evolution -parse-as-library -package-name Package -experimental-lazy-typecheck -experimental-skip-all-function-bodies -experimental-serialize-external-decls-only
+// RUN: %target-swift-frontend -swift-version 5 %S/../Inputs/lazy_typecheck.swift -module-name lazy_typecheck -typecheck -emit-module-interface-path %t/lazy_typecheck.swiftinterface -enable-library-evolution -parse-as-library -package-name Package -experimental-lazy-typecheck
 // RUN: %FileCheck %s < %t/lazy_typecheck.swiftinterface
 
 // RUN: rm -rf %t/*.swiftmodule