Revert "Reinitialize GL_VENDOR string when GPU switches"

This reverts commit 0f083ab026.

Reason for revert: Seems to be blocking the ANGLE auto-roller (see: http://anglebug.com/5422)

Original change's description:
> Reinitialize GL_VENDOR string when GPU switches
>
> We already update the GL_RENDERER string. We should do the same for
> GL_VENDOR so this information is passed along correctly.
>
> Bug: chromium:1152212
> Change-Id: I639700bfebdc9e77ec3c6b41fcd6516e8c32139d
> Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2560824
> Reviewed-by: Jonah Ryan-Davis <jonahr@google.com>
> Reviewed-by: Geoff Lang <geofflang@chromium.org>
> Commit-Queue: Jonah Ryan-Davis <jonahr@google.com>

TBR=geofflang@chromium.org,syoussefi@chromium.org,jonahr@google.com

Change-Id: I01bbb08946d16cf821f4fb1bfd8b1cade1ab70f1
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:1152212
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2567460
Reviewed-by: Ian Elliott <ianelliott@google.com>
Commit-Queue: Ian Elliott <ianelliott@google.com>

src/libANGLE/Display.cpp

@@ -2042,10 +2042,8 @@ void Display::returnScratchBufferImpl(angle::ScratchBuffer scratchBuffer,
     bufferVector->push_back(std::move(scratchBuffer));
 }
 
-Error Display::handleGPUSwitch()
+egl::Error Display::handleGPUSwitch()
 {
-    ANGLE_TRY(mImplementation->handleGPUSwitch());
-    initVendorString();
-    return NoError();
+    return mImplementation->handleGPUSwitch();
 }
 }  // namespace egl