fix(ci): use github-hosted runner for nightly android build

build-submit-android.yml inherited runs-on: Linux-x64-32core from
upstream (bluesky-social/social-app bluesky-social#9404), a self-hosted runner label
that only exists in Bluesky's org. In blacksky-algorithms no runner
carries that label, so the nightly Android job sat queued until the 24h
maximum-wait timeout every night.

Switch to ubuntu-latest, matching the inline Android job in
bundle-deploy-eas-update.yml and the rest of the repo's workflows.

Author: rishibalakrishnan

.github/workflows/build-submit-android.yml

@@ -32,7 +32,7 @@ jobs:
   build:
     if: github.repository == 'blacksky-algorithms/blacksky.community'
     name: Build and Submit Android
-    runs-on: Linux-x64-32core
+    runs-on: ubuntu-latest
     concurrency:
       group: android-build
       cancel-in-progress: false