Run WebView tests with BFCache in android-bfcache-rel

The CL enables BackForwardCache in WebView tests in the CI bot
android-bfcache-rel.
The current tests in android-bfcache-rel are run with the BFCache
feature disabled. The newly added tests will run WebView
instrumentation tests and CTS tests with the WebViewBackForwardCache
feature enabled to verify the behavior for the newly added BFCache
feature in the WebView. The default test config runs tests with BFCache
for all platform except WebView. The android-bfcache-rel bot will cover
the reverse case to run tests with BFCache only on WebView.

Bug: 331587668
Change-Id: I4a0b72d78b9391d2aec08573593a6daac8b6f073
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5600898


Commit-Queue: Jiacheng Guo <gjc@google.com>
Reviewed-by: Wanda Mora <morawand@google.com>
Reviewed-by: Richard (Torne) Coles <torne@chromium.org>
Reviewed-by: Rakina Zata Amni <rakina@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1313148}