locale: rm llm_proofreader directory during build

Deletes the llm_proofreader directory during the build so
these scripts aren't bundled into the binaries.

contrib/locale/build_cleanlocale.sh

@@ -13,4 +13,5 @@ LOCALE="$PROJECT_ROOT/electrum/locale/"
 cd "$LOCALE"
 git clean -ffxd
 git reset --hard
+rm -rf llm_proofreader
 "$CONTRIB_LOCALE/build_locale.sh" "$LOCALE/locale" "$LOCALE/locale"