Revert "Re-enable testAutoFetchRequestRetainedOnOtherTabClosed"

This reverts commit 4eb3219b.

Reason for revert: Still failing consistently on KitKat Tablet Tester:

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/KitKat%20Tablet%20Tester

Example:

https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8920505223364583920/+/steps/chrome_public_test_apk_on_Android_device_Nexus_7__2013_/0/logs/org.chromium.chrome.browser.offlinepages.OfflinePageAutoFetchTest_testAutoFetchRequestRetainedOnOtherTabClosed__status_FAILURE_/0

Original change's description:
> Re-enable testAutoFetchRequestRetainedOnOtherTabClosed
> 
> I ran the test 40 times on my local device, and it passed each one.
> Hopefully the previous changes to this test file have fixed the flake.
> 
> Bug: 923212
> Change-Id: Ic8b3e6e6b82b60d14bdef9975d5d70e256dcf1b7
> Reviewed-on: https://chromium-review.googlesource.com/c/1470634
> Reviewed-by: Carlos Knippschild <carlosk@chromium.org>
> Commit-Queue: Dan H <harringtond@google.com>
> Cr-Commit-Position: refs/heads/master@{#635255}

TBR=carlosk@chromium.org,harringtond@google.com

Change-Id: I697b84adf6ed3def942aaa0653488d89b8b6107d
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 923212
Reviewed-on: https://chromium-review.googlesource.com/c/1489095Reviewed-by: Matthew Jones <mdjones@chromium.org>
Commit-Queue: Matthew Jones <mdjones@chromium.org>
Cr-Commit-Position: refs/heads/master@{#635570}

chrome/android/javatests/src/org/chromium/chrome/browser/offlinepages/OfflinePageAutoFetchTest.java

@@ -22,6 +22,7 @@ import org.chromium.base.ThreadUtils;
 import org.chromium.base.metrics.RecordHistogram;
 import org.chromium.base.test.util.CallbackHelper;
 import org.chromium.base.test.util.CommandLineFlags;
+import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
 import org.chromium.chrome.browser.ChromeActivity;
 import org.chromium.chrome.browser.ChromeSwitches;
@@ -262,6 +263,7 @@ public class OfflinePageAutoFetchTest {
     @Test
     @MediumTest
     @Feature({"OfflineAutoFetch"})
+    @DisabledTest(message = "Flaky: https://crbug.com/883486#c20")
     public void testAutoFetchRequestRetainedOnOtherTabClosed() throws Exception {
         startWebServer();
         final String testUrl = mWebServer.getBaseUrl();