Remove Chrome version from GPU program cache validity key

Reverts the Chrome-version component added in crrev.com/c/8162820, so
the Dawn revision is once again the sole key for the serialized GPU
model data.

The version check invalidates the cache on every Chrome milestone,
forcing a full shader recompile for all users on each update. Per
crbug.com/538727789, a stale cache is acceptable in practice: the cost
is missing newer ML Drift kernel optimizations, not incorrect results.
The remaining theoretical risk (an ML Drift change that alters the
shader binding layout without changing the fingerprint) is better
covered by an ML Drift-side test using a valid serialized model,
mirroring the existing Vulkan test, then by a Chrome-side version bump.

Bug: 538727789
Test: components_unittests --gtest_filter=*GpuCache*:*ManifestSolutionFactory*
Test: services_unittests --gtest_filter=*OnDeviceModel*
Change-Id: Ie4822c84b954e96e1ee35dae5a12e8f047090444
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/8446421
Reviewed-by: Steven Holte <holte@chromium.org>
Reviewed-by: Robbie McElrath <rmcelrath@chromium.org>
Reviewed-by: Nathan Memmott <memmott@chromium.org>
Commit-Queue: Alan Ding <alanding@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1704136}