AK: Enable format string checking in Clang builds

Format string checking was disabled in Clang-based builds due to a
compiler bug: llvm/llvm-project#51182. Now
that the requirement has been raised to Clang 17, that is no longer
necessary.

This has been tested to work correctly with Apple Clang 15.0.0 (which is
the *least modern* supported compiler), as well as CLion 2024.1's
bundled Clangd.

AK/CheckedFormatString.h

@@ -11,14 +11,6 @@
 #include <AK/Array.h>
 #include <AK/StringView.h>
 
-#ifdef ENABLE_COMPILETIME_FORMAT_CHECK
-// FIXME: Seems like clang doesn't like calling 'consteval' functions inside 'consteval' functions quite the same way as GCC does,
-//        it seems to entirely forget that it accepted that parameters to a 'consteval' function to begin with.
-#    if defined(AK_COMPILER_CLANG)
-#        undef ENABLE_COMPILETIME_FORMAT_CHECK
-#    endif
-#endif
-
 #ifdef ENABLE_COMPILETIME_FORMAT_CHECK
 namespace AK::Format::Detail {