bindings: Stop creating 'lextab' file in the code tree.

Prevents third_party/ply/lex.py from creating 'lextab' file.

In the old bindings code generator, we created a new process per
.idl file to produce auto-generated C++ files, so it was important
to save 'lextab' file and reuse it among thousands processes.

In the new bindings code generator, we creates a new process per
a set of .idl files of the same component (core, modules, etc.),
so it's no longer important to save 'lextab' file to speed up
the initialization of the process.

We're now creating 'lextab' file outside of out/Default/ directory
making the code tree dirty, so it's better to stop the creation.

Bug: 1312050
Change-Id: Idfe9e7ee569b19b0df2cd4816d0df7016993ddd5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3570851
Reviewed-by: Kentaro Hara <haraken@chromium.org>
Commit-Queue: Yuki Shiino <yukishiino@chromium.org>
Cr-Commit-Position: refs/heads/main@{#988909}
NOKEYCHECK=True
GitOrigin-RevId: 9f00419c591ee12d90c2ed11a050bc6403f3ba39