Revert "Add off-main-thread-worker-script-fetch/external/wpt/referrer-policy"

This reverts commit 98dc58ec.

Reason for revert: crbug.com/906964

Original change's description:
> Add off-main-thread-worker-script-fetch/external/wpt/referrer-policy
> 
> Bug: 835717, 880027
> Change-Id: I074ea4b911132477853bf95be70a36b7d62c4f79
> Reviewed-on: https://chromium-review.googlesource.com/c/1330903
> Reviewed-by: Hiroki Nakagawa <nhiroki@chromium.org>
> Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#609534}

TBR=hiroshige@chromium.org,nhiroki@chromium.org

Change-Id: Ic9c46e2efd39d774c3833aef324a654010f65bc2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 835717, 880027, 906964
Reviewed-on: https://chromium-review.googlesource.com/c/1344257Reviewed-by: Hiroshige Hayashizaki <hiroshige@chromium.org>
Commit-Queue: Hiroshige Hayashizaki <hiroshige@chromium.org>
Cr-Commit-Position: refs/heads/master@{#609732}

third_party/WebKit/LayoutTests/VirtualTestSuites

@@ -694,11 +694,6 @@
     "base": "external/wpt/workers",
     "args": ["--enable-blink-features=OffMainThreadWorkerScriptFetch"]
   },
-  {
-    "prefix": "off-main-thread-worker-script-fetch",
-    "base": "external/wpt/referrer-policy",
-    "args": ["--enable-blink-features=OffMainThreadWorkerScriptFetch"]
-  },
   {
     "prefix": "off-main-thread-worker-script-fetch",
     "base": "fast/workers",

third_party/WebKit/LayoutTests/virtual/off-main-thread-worker-script-fetch/external/wpt/referrer-policy/README.txt

-This directory is for testing off-the-main-thread top-level worker classic
-script loading. See https://crbug.com/835717.