fix: Attempt to fix nightly test (#8222)

This PR attempts to fix a nightly test

.github/workflows/sepolia-test.yml

@@ -1,7 +1,8 @@
 name: Run public testnet test
 on:
+  workflow_dispatch:
   schedule:
-    - cron: "00 12 * * 1-5"
+    - cron: "00 08 * * 1-5"
 
 concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
@@ -61,12 +62,14 @@ jobs:
       - uses: actions/checkout@v4
         with: { ref: "${{ env.GIT_COMMIT }}" }
       - uses: ./.github/ci-setup-action
+        with:
+          # must be globally unique for build x runner
+          concurrency_key: public-testnet-x86
       - name: Setup and Test
         timeout-minutes: 40
         uses: ./.github/ensure-tester-with-images
         with:
-          # big machine since we're doing proving
-          runner_type: "64core-tester-x86"
+          runner_type: "8core-tester-x86"
           builder_type: builder-x86
           # these are copied to the tester and expected by the earthly command below
           # if they fail to copy, it will try to build them on the tester and fail