Removed switches::kNoSandbox switch on OS_WIN.

It was previously required to prevent chromium_browsertests from
crashing, however, that does not seem to be the case anymore.

Change-Id: Ibff440948fe268db0cc0e0f635a5766beb032da8
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2454372
Commit-Queue: Peter Kvitek <kvitekp@chromium.org>
Commit-Queue: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Andrey Kosyakov <caseq@chromium.org>
Reviewed-by: Peter Kvitek <kvitekp@chromium.org>
Auto-Submit: Peter Kvitek <kvitekp@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815315}

headless/lib/headless_content_main_delegate.cc

@@ -231,7 +231,6 @@ bool HeadlessContentMainDelegate::BasicStartupComplete(int* exit_code) {
   command_line->AppendSwitch(::blink::switches::kAllowPreCommitInput);
 
 #if defined(OS_WIN)
-  command_line->AppendSwitch(sandbox::policy::switches::kNoSandbox);
   command_line->AppendSwitch(
       ::switches::kDisableGpuProcessForDX12InfoCollection);
 #endif