AW: remove HttpCacheTest from the filter

This got fixed in http://crrev/c/1314133 and http://crrev/c/1319334.

R=jam@chromium.org

Bug: 893577
Bug: 887538
Test: N/A
Change-Id: Ib012ff2f18e5e2b92ad6167d3de48154b4cd1b04
Cq-Include-Trybots: master.tryserver.chromium.android:android_mojo
Reviewed-on: https://chromium-review.googlesource.com/c/1322354Reviewed-by: John Abd-El-Malek <jam@chromium.org>
Commit-Queue: Nate Fischer <ntfschr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#606083}

testing/buildbot/filters/mojo.fyi.network_webview_instrumentation_test_apk.filter

@@ -139,9 +139,6 @@
 -org.chromium.android_webview.test.CookieManagerTest.testThirdPartyCookiesArePerWebview
 -org.chromium.android_webview.test.CookieManagerTest.testThirdPartyJavascriptCookie
 
-# https://crbug.com/893577
--org.chromium.android_webview.test.HttpCacheTest.testHttpCacheIsInsideCacheDir
-
 # https://crbug.com/893579
 -org.chromium.android_webview.test.KeySystemTest.testNotSupportFooKeySystem
 -org.chromium.android_webview.test.KeySystemTest.testSupportClearKeySystem