Move profile_provider_unittest from //:chromiumos_preflight to //:gn_all

profile_provider_unittest is a big target, and takes some time to build:
https://chromium-build-stats.appspot.com/ninja_log/2020/04/15/luci-chrome-ci-xenial-us-west1-c-highmem-16-1-jm5p/ninja_log.luci-chrome-ci-xenial-us-west1-c-highmem-16-1-jm5p.chrome-bot.20200415-113309.9739.gz/trace.html

By moving it into //:gn_all, we can speed up the build time of
//:chromiumos_preflight while still allowing bots that run the test
to find the target.

Change-Id: I5881faf0b11a22899f8639c55dc28dd554cd8906
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2150815Reviewed-by: Nico Weber <thakis@chromium.org>
Commit-Queue: Ben Pastene <bpastene@chromium.org>
Cr-Commit-Position: refs/heads/master@{#759711}

BUILD.gn

@@ -435,6 +435,7 @@ group("gn_all") {
       "//ash/app_list:app_list_demo",
       "//ash/app_list:app_list_unittests",
       "//ash/keyboard/ui:keyboard_unittests",
+      "//chrome/browser/metrics/perf:profile_provider_unittest",
       "//chrome/test:usage_time_limit_unittests",
       "//chromeos:chromeos_unittests",
       "//chromeos/components:chromeos_components_unittests",
@@ -917,7 +918,6 @@ if (is_chromeos) {
     testonly = true
     deps = [
       "//chrome",
-      "//chrome/browser/metrics/perf:profile_provider_unittest",
       "//chrome/test/chromedriver",
       "//components/chromeos_camera:jpeg_decode_accelerator_unittest",
       "//components/exo/wayland:wayland_client_perftests",