Move strings in heap-symbols.h that only used inside V8_INTL_SUPPORT
under INTERNALIZED_STRING_LIST_GENERATOR_INTL so non intl users won't
use unnecessary memory. Also avoid two NewStringFromStaticChars calls
for string already defined in heap-symbols.h.

Bug: v8:8256
Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng
Change-Id: I65dbc34639064d6d4c7d1786405b8b3af666bc2a
Reviewed-on: https://chromium-review.googlesource.com/c/1268761Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56456}