Reclassify the Borealis launcher as a default app.

It can only get on a device by being preinstalled, so this seems
like a more appropriate category. More importantly, it should make
app count metrics slightly easier to interpret.

BUG=b:202065545
TEST=With Borealis enabled but not installed, view chrome://histograms to check that Apps.AppsCountPerInstallReason.Borealis.Preload is 1

Change-Id: Ie2768aa92921c8abe492b40236fb2931dac373a5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3302293
Commit-Queue: Chloe Pelling <cpelling@google.com>
Commit-Queue: Nancy Wang <nancylingwang@chromium.org>
Auto-Submit: Chloe Pelling <cpelling@google.com>
Reviewed-by: Nancy Wang <nancylingwang@chromium.org>
Cr-Commit-Position: refs/heads/main@{#945543}

chrome/browser/apps/app_service/publishers/borealis_apps.cc

@@ -88,7 +88,7 @@ apps::mojom::AppPtr GetBorealisLauncher(Profile* profile, bool allowed) {
       allowed ? apps::mojom::Readiness::kReady
               : apps::mojom::Readiness::kDisabledByPolicy,
       l10n_util::GetStringUTF8(IDS_BOREALIS_APP_NAME),
-      apps::mojom::InstallReason::kUser);
+      apps::mojom::InstallReason::kDefault);
 
   app->icon_key = apps::mojom::IconKey::New(
       apps::mojom::IconKey::kDoesNotChangeOverTime,