[l10n] Simplify 'npm run collect-strings'
[l10n] Simplify 'npm run collect-strings'

Since en-US.json and en-XL.json are generated at build time,
collect-strings.js's only job is to create en-US.ctc.json when we
export the DevTools UI strings into our translation pipeline.

As such we can simplify the script a bit and:
  * Not create the pseudo local
  * No baking of *.ctc.json files. That's handled by a separate script.

R=d8d88e7d7e77f69e23d1d1432231196fb8e02a62@chromium.org

Bug: 1185727
Change-Id: Id333d098dc8632f3e381824be55b30c59fe970e0
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/4047684
Commit-Queue: Simon Zünd <38944668e9e2ca98ccd0275b53370f90fa55c113@chromium.org>
Reviewed-by: Alex Rudenko <d8d88e7d7e77f69e23d1d1432231196fb8e02a62@chromium.org>

ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend,ChromeDevTools/devtools-frontend