Revert "[Fuchsia] Reenable protected mode in WebEngine"

This reverts commit a2c0ced3.

Reason for revert: Tentative revert to help with system OOM issues.

Original change's description:
> [Fuchsia] Reenable protected mode in WebEngine
> 
> Bug: 982922, fuchsia:24570
> Change-Id: If9fb495249488c43f97e4451a14f0193911d600f
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1804527
> Reviewed-by: Sergey Ulanov <sergeyu@chromium.org>
> Commit-Queue: Emircan Uysaler <emircan@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#697683}

TBR=sergeyu@chromium.org,emircan@chromium.org

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: 982922, fuchsia:24570
Change-Id: I94ae35ec8d84d96af757068ab552d3942318048b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1894103Reviewed-by: Emircan Uysaler <emircan@chromium.org>
Commit-Queue: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#711547}

fuchsia/engine/context_provider_impl.cc

@@ -257,10 +257,6 @@ void ContextProviderImpl::Create(
                                      switches::kGrContextTypeVulkan);
   }
 
-  if (enable_protected_graphics) {
-    launch_command.AppendSwitch(switches::kEnforceVulkanProtectedMemory);
-  }
-
   if (enable_widevine) {
     launch_command.AppendSwitch(switches::kEnableWidevine);
   }