Revert "Re-enable testPaymentsIntegrationCheckboxClearsServerAutofillCreditCards"

This reverts commit 4e6c1d9e.

Reason for revert: Test still very flaky (see bug)

Original change's description:
> Re-enable testPaymentsIntegrationCheckboxClearsServerAutofillCreditCards
> 
> Test succeeded 10/10 times locally, and no log data available on the bug
> or flakiness dashboard (disabled >6 months ago). Re-enabling to monitor
> whether flakiness still exists.
> 
> Pre-emptively increasing timeout to MediumTest either way since this
> test is more than a simple unit test.
> 
> Bug: 994726
> Change-Id: Iaa645356906b17ff17c44cc49c4c76c7b9dac4d3
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2134204
> Reviewed-by: Tommy Nyquist <nyquist@chromium.org>
> Commit-Queue: Natalie Chouinard <chouinard@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#755973}

TBR=nyquist@chromium.org,chouinard@chromium.org

Change-Id: I82b8a2877bda92fc6d864d58f97b553130e820b1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 994726
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2135327Reviewed-by: Natalie Chouinard <chouinard@chromium.org>
Commit-Queue: Natalie Chouinard <chouinard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#756290}

chrome/android/javatests/src/org/chromium/chrome/browser/sync/ManageSyncSettingsTest.java

@@ -6,7 +6,6 @@ package org.chromium.chrome.browser.sync;
 
 import android.app.Dialog;
 import android.support.test.InstrumentationRegistry;
-import android.support.test.filters.MediumTest;
 import android.support.test.filters.SmallTest;
 import android.widget.Button;
 import android.widget.EditText;
@@ -24,6 +23,7 @@ import org.junit.Test;
 import org.junit.runner.RunWith;
 
 import org.chromium.base.test.util.CommandLineFlags;
+import org.chromium.base.test.util.DisabledTest;
 import org.chromium.base.test.util.Feature;
 import org.chromium.base.test.util.FlakyTest;
 import org.chromium.chrome.R;
@@ -203,8 +203,9 @@ public class ManageSyncSettingsTest {
         assertPaymentsIntegrationEnabled(true);
     }
 
+    @DisabledTest(message = "crbug.com/994726")
     @Test
-    @MediumTest
+    @SmallTest
     @Feature({"Sync"})
     public void testPaymentsIntegrationCheckboxClearsServerAutofillCreditCards() {
         mSyncTestRule.setUpTestAccountAndSignIn();