[WebOTP] remove unnecessary flag in tests

The flag name has changed to WebOTP but the test was not updated.
Despite this it was working as expected since the test also uses the
broader "kEnableExperimentalWebPlatformFeatures" flags.

Removing the out-dated flag from the test.

Bug: None

Change-Id: Icadf911858b8165bd6c7148c7545e93ac46680f9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2491003
Commit-Queue: Yi Gu <yigu@chromium.org>
Auto-Submit: Majid Valipour <majidvp@chromium.org>
Reviewed-by: Yi Gu <yigu@chromium.org>
Cr-Commit-Position: refs/heads/master@{#825366}

content/browser/sms/sms_browsertest.cc

@@ -47,8 +47,6 @@ class SmsBrowserTest : public ContentBrowserTest {
 
   void SetUpCommandLine(base::CommandLine* command_line) override {
     ContentBrowserTest::SetUpCommandLine(command_line);
-    command_line->AppendSwitchASCII(switches::kEnableBlinkFeatures,
-                                    "WebOTPService");
     command_line->AppendSwitch(
         switches::kEnableExperimentalWebPlatformFeatures);
     command_line->AppendSwitchASCII(switches::kWebOtpBackend,