[iOS] Remove deprecated method signOutAndClearAccounts in ChromeEarlGrey

This method is no longer used, clean up sign-in utilities.

Bug: 1103274
Change-Id: I2b5a68c869d723e2216ab41fdf984948ce5b1eb5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2352804
Auto-Submit: Nohemi Fernandez <fernandex@chromium.org>
Commit-Queue: Eugene But <eugenebut@chromium.org>
Reviewed-by: Eugene But <eugenebut@chromium.org>
Cr-Commit-Position: refs/heads/master@{#797680}

ios/chrome/test/earl_grey/chrome_earl_grey.h

@@ -353,11 +353,6 @@ id ExecuteJavaScript(NSString* javascript, NSError* __autoreleasing* out_error);
 // the operation fails.
 - (void)signOutAndClearIdentities;
 
-// Same as signOutAndClearIdentities.
-//
-// DEPRECATED in favor of signOutAndClearIdentities
-- (void)signOutAndClearAccounts;
-
 #pragma mark - Sync Utilities (EG2)
 
 // Waits for sync to be initialized or not. If not succeeded a GREYAssert is

ios/chrome/test/earl_grey/chrome_earl_grey.mm

@@ -850,16 +850,12 @@ GREY_STUB_CLASS_IN_APP_MAIN_QUEUE(ChromeEarlGreyAppInterface)
                              @"Failed waiting for identities to be cleared");
 }
 
-- (void)signOutAndClearAccounts {
-  [self signOutAndClearIdentities];
-}
+#pragma mark - Bookmarks Utilities (EG2)
 
 - (void)addBookmarkWithSyncPassphrase:(NSString*)syncPassphrase {
   [ChromeEarlGreyAppInterface addBookmarkWithSyncPassphrase:syncPassphrase];
 }
 
-#pragma mark - Bookmarks Utilities (EG2)
-
 - (void)waitForBookmarksToFinishLoading {
   EG_TEST_HELPER_ASSERT_NO_ERROR(
       [ChromeEarlGreyAppInterface waitForBookmarksToFinishinLoading]);