src: remove .h if -inl.h is already included

This commit removes the normal header file include if an internal one
is specified as per the CPP_STYLE_GUIDE.

PR-URL: https://github.com/nodejs/node/pull/21381
Reviewed-By: Matheus Marchini <matheus@sthima.com>
Reviewed-By: Gus Caplan <me@gus.host>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Ujjwal Sharma <usharma1998@gmail.com>

src/node_encoding.cc

@@ -1,8 +1,6 @@
 #include "node.h"
-#include "env.h"
 #include "env-inl.h"
 #include "string_bytes.h"
-#include "util.h"
 #include "util-inl.h"
 #include "v8.h"