Revert "ChromeOS: Migrate diagnostics UI to use TypeScript mojo bindings"

This reverts commit b554f0238a0b2a9d27b54f40ade97abe5c7f912b.

Reason for revert: Tree broken https://ci.chromium.org/ui/p/chromium/builders/ci/linux-cfm-rel/65936/overview

Original change's description:
> ChromeOS: Migrate diagnostics UI to use TypeScript mojo bindings
>
> This UI is already using TypeScript for other files, so will benefit
> from improved typechecking by migrating to TS bindings instead of
> Closure.
>
> Also fixing various type errors discovered by the migration, e.g.
> missing fields in Mojo structs are always null and not undefined at
> runtime, but the code was erroneously assuming they could be
> undefined.
>
> Bug: 384098175
> Change-Id: I1dd662ba00878c8806b68c0c6271e173e15f5076
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6107431
> Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
> Code-Coverage: findit-for-me@appspot.gserviceaccount.com <findit-for-me@appspot.gserviceaccount.com>
> Reviewed-by: Ethan Cheng <yycheng@google.com>
> Cr-Commit-Position: refs/heads/main@{#1398612}

Bug: 384098175
Change-Id: I34aab299e55aa65cdbf92fde024da6d2ecede194
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6109100
Auto-Submit: Ari Chivukula <arichiv@chromium.org>
Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Owners-Override: Ari Chivukula <arichiv@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Commit-Queue: Ari Chivukula <arichiv@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1398625}