[CI] Move some PR builds over to the faster agents

Should speed up the CI gate builds. May have to revert this if it
proves too expensive.

.github/workflows/buildAndTest.yml

@@ -152,9 +152,17 @@ jobs:
   build-circt:
     name: Build and Test
     needs: sanity-check
-    runs-on: ubuntu-latest
+    # Run on an internal MSFT subscription. Please DO NOT use this for any other
+    # workflows without talking to John Demme (john.demme@microsoft.com, GH
+    # teqdruid) first. We may lose funding for this if it ends up costing too
+    # much.
+    # If individual jobs fail due to timeouts or disconnects, please report to
+    # John and re-run the job.
+    runs-on: ["self-hosted", "1ES.Pool=1ES-CIRCT-builds"]
     container:
       image: ghcr.io/circt/images/circt-ci-build:20230126201226
+      volumes:
+        - /mnt:/__w/circt
     strategy:
       matrix:
         compiler:

.github/workflows/shortIntegrationTests.yml

@@ -21,9 +21,17 @@ jobs:
   # integration testing prerequisite installed.
   build-circt:
     name: Build and Test
-    runs-on: ubuntu-latest
+    # Run on an internal MSFT subscription. Please DO NOT use this for any other
+    # workflows without talking to John Demme (john.demme@microsoft.com, GH
+    # teqdruid) first. We may lose funding for this if it ends up costing too
+    # much.
+    # If individual jobs fail due to timeouts or disconnects, please report to
+    # John and re-run the job.
+    runs-on: ["self-hosted", "1ES.Pool=1ES-CIRCT-builds"]
     container:
       image: ghcr.io/circt/images/circt-integration-test:v12.2
+      volumes:
+        - /mnt:/__w/circt
     strategy:
       # Keep the 'matrix' strategy with one data point to make it obvious that
       # this is one point in the overall matrix.