ci: migrate runs-on to Twilio runner labels

Repoints runs-on to the standard Twilio runner labels for this repo.
Unmapped runners (macOS, matrix expressions, etc.) left as-is.

Author: charlottestjohn

.github/workflows/ci.yml

@@ -2,7 +2,7 @@ on: [push, pull_request]
 name: Test
 jobs:
   test:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-latest-large
     steps:
     - name: Install Go
       uses: actions/setup-go@v5