Removed Platform Provided Trust Tokens

As we don't currently plan to release platform provided trust tokens, this CL removes
the existing code implementing them.

Fixed: 1395146

Change-Id: I71b395fad7ef4242c70c9cf281e02ecdc2234f76
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4052381
Reviewed-by: Yaron Friedman <yfriedman@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Reviewed-by: danakj <danakj@chromium.org>
Reviewed-by: Richard Coles <torne@chromium.org>
Reviewed-by: Daniel Murphy <dmurph@chromium.org>
Reviewed-by: David Schinazi <dschinazi@chromium.org>
Reviewed-by: Steven Valdez <svaldez@chromium.org>
Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Sam Schlesinger <samschlesinger@google.com>
Reviewed-by: Max Curran <curranmax@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1080199}