Use available Ubuntu runners in workflows

Author: cipolleschi

.github/workflows/nightly.yml

@@ -35,7 +35,7 @@ jobs:
     needs: [prebuild_apple_dependencies]
 
   build_android:
-    runs-on: 8-core-ubuntu
+    runs-on: ubuntu-latest
     if: github.repository == 'react/react-native'
     needs: [set_release_type]
     container:
@@ -57,7 +57,7 @@ jobs:
           gradle-cache-encryption-key: ${{ secrets.GRADLE_CACHE_ENCRYPTION_KEY }}
 
   build_npm_package:
-    runs-on: 8-core-ubuntu
+    runs-on: ubuntu-latest
     needs:
       [
         set_release_type,

.github/workflows/publish-release.yml

@@ -52,7 +52,7 @@ jobs:
     needs: [prebuild_apple_dependencies]
 
   build_npm_package:
-    runs-on: 8-core-ubuntu
+    runs-on: ubuntu-latest
     needs:
       [
         set_release_type,

.github/workflows/test-all.yml

@@ -201,7 +201,7 @@ jobs:
           working-directory: /tmp/RNTestProject
 
   test_e2e_android_templateapp:
-    runs-on: 4-core-ubuntu
+    runs-on: ubuntu-latest
     needs: build_npm_package
     strategy:
       fail-fast: false
@@ -269,7 +269,7 @@ jobs:
           working-directory: /tmp/RNTestProject
 
   run_fantom_tests:
-    runs-on: 8-core-ubuntu
+    runs-on: ubuntu-latest
     needs: [set_release_type]
     container:
       image: reactnativecommunity/react-native-android:v20.0
@@ -307,7 +307,7 @@ jobs:
           gradle-cache-encryption-key: ${{ secrets.GRADLE_CACHE_ENCRYPTION_KEY }}
 
   test_e2e_android_rntester:
-    runs-on: 4-core-ubuntu
+    runs-on: ubuntu-latest
     needs: [build_android]
     strategy:
       fail-fast: false
@@ -337,7 +337,7 @@ jobs:
           flavor: ${{ matrix.flavor }}
 
   build_npm_package:
-    runs-on: 8-core-ubuntu
+    runs-on: ubuntu-latest
     needs:
       [
         set_release_type,
@@ -360,7 +360,7 @@ jobs:
           gradle-cache-encryption-key: ${{ secrets.GRADLE_CACHE_ENCRYPTION_KEY }}
 
   test_android_helloworld:
-    runs-on: 4-core-ubuntu
+    runs-on: ubuntu-latest
     needs: build_npm_package
     container:
       image: reactnativecommunity/react-native-android:v20.0