Reland "[fuchsia] Remove use of ambient VMEX capabilities"

This is a second reland of
commit 32d1466c6def9112df62366e9d9872b282ba1f25, after addressing
security policy & routing issues up-stream.

- Remove job_policy_ambient_mark_vmo_exec from all component
  manifests.
- Remove most usage of the ambient-VMEX-capable ELF test runner.

Some use of the ambient-VMEX ELF runner remains, to support tests
which run SwiftShader in-process, which requires ambient-VMEX for its
shader JIT.

The test CML fragment for the VMEX-capable ELF test runner is also
still required by out-of-tree dependencies, notably ANGLE.

Bug: 1290907, 1185811, 1022542
Change-Id: I7bd4308469abf350ee8ea48a1e6371bc2f11284c
Cq-Include-Trybots: luci.chrome.try:fuchsia-smoke-astro,fuchsia-smoke-sherlock
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4626516
Owners-Override: Wez <wez@chromium.org>
Reviewed-by: David Dorwin <ddorwin@chromium.org>
Commit-Queue: David Dorwin <ddorwin@chromium.org>
Auto-Submit: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1161336}

diff --git a/cc/BUILD.gn b/cc/BUILD.gn
index f3dd9ce..182f2f1 100644
--- a/cc/BUILD.gn
+++ b/cc/BUILD.gn

@@ -930,12 +930,15 @@
   }
 
   if (is_fuchsia) {
-    # TODO(https://crbug.com/1185811): Investigate removing the requirement for
-    # job_policy_ambient_mark_vmo_exec for the sake of V8's allocator in tests.
+    # TODO(https://crbug.com/1022542): Some of these tests use SwiftShader,
+    # which requires ambient VMEX.
     test_runner_shard = "//build/config/fuchsia/test/elf_test_ambient_exec_runner.shard.test-cml"
 
     additional_manifest_fragments = [
       "//build/config/fuchsia/test/fonts.shard.test-cml",
+
+      # TODO(https://crbug.com/1185811): Investigate removing the requirement
+      # for VmexResource.
       "//build/config/fuchsia/test/mark_vmo_executable.shard.test-cml",
       "//third_party/fuchsia-sdk/sdk/pkg/vulkan/client.shard.cml",
     ]