[//cc] Clean up PictureLayerImpl unittest for low-res tiling elimination

Folds the "NoLowResTiling" test fixture into its base class and
eliminates duplicate tests [1][2].

[1] https://source.chromium.org/chromium/chromium/src/+/main:cc/layers/picture_layer_impl_unittest.cc;l=600?q=PendingLayerOnlyHas&sq=&ss=chromium
[2] https://source.chromium.org/chromium/chromium/src/+/main:cc/layers/picture_layer_impl_unittest.cc;l=1066?q=_ReleaseTileResources&ss=chromium

Bug: 418234930
Change-Id: Icab792579d2607cb7bbfef115c0d9f963c59c78e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6632566
Reviewed-by: Vasiliy Telezhnikov <vasilyt@chromium.org>
Commit-Queue: Colin Blundell <blundell@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1472895}