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

@@ -4,7 +4,7 @@ on: [push]
 
 jobs:
   test-and-build:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-latest-large
 
     strategy:
       matrix: