Revert "Structured Headers: Include all public tests"

This reverts commit 068d6078.

Reason for revert: Causes compile to hang for https://ci.chromium.org/p/chromium/builders/ci/Mac%20ASan%2064%20Builder

Original change's description:
> Structured Headers: Include all public tests
> 
> This imports all of the tests from the public test repository at
> https://github.com/httpwg/structured-header-tests, which have been
> automatically converted from JSON to C++ unit tests.
> 
> Tests which were already present in structured_headers_unittest.cc
> have been removed from that file, to avoid needless redundancy.
> 
> Bug: 1069790
> Change-Id: I05536c36cb66c7dda43aab2f6c5ae77961120a6a
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2146237
> Commit-Queue: Ian Clelland <iclelland@chromium.org>
> Reviewed-by: Asanka Herath <asanka@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#759015}

TBR=iclelland@chromium.org,asanka@chromium.org

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

Bug: 1069790
Change-Id: I398e00aaa9903872475f8c5cb5f2513f99e38b69
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2159370Reviewed-by: Garrett Beaty <gbeaty@chromium.org>
Commit-Queue: Garrett Beaty <gbeaty@chromium.org>
Cr-Commit-Position: refs/heads/master@{#761024}

net/BUILD.gn

@@ -4289,7 +4289,6 @@ test("net_unittests") {
     "http/http_vary_data_unittest.cc",
     "http/mock_allow_http_auth_preferences.cc",
     "http/mock_allow_http_auth_preferences.h",
-    "http/structured_headers_generated_unittest.cc",
     "http/structured_headers_unittest.cc",
     "http/transport_security_persister_unittest.cc",
     "http/transport_security_state_unittest.cc",