ci: move timing tests to nightly gauntlet (#7910)

Test_Runner_Timing was one of our flakiest tests before.

.github/workflows/nightly-gauntlet.yaml

@@ -1,15 +1,16 @@
-name: nightly-flake
+# The nightly-gauntlet runs tests that are either too flaky or too slow to block
+# every PR.
+name: nightly-gauntlet
 on:
   schedule:
     # Every day at midnight
     - cron: "0 0 * * *"
   workflow_dispatch:
-  # For testing purposes
-  # push:
-  #   paths:
-  # - ".github/workflows/nightly-flake.yaml"
+  push:
+    branch:
+      - nightly-gauntlet
 jobs:
-  test-go-race:
+  go-race:
     # While GitHub's toaster runners are likelier to flake, we want consistency
     # between this environment and the regular test environment for DataDog
     # statistics and to only show real workflow threats.
@@ -38,3 +39,20 @@ jobs:
         if: always()
         with:
           api-key: ${{ secrets.DATADOG_API_KEY }}
+
+  go-timing:
+    # We run these tests with p=1 so we don't need a lot of compute.
+    runs-on: "buildjet-2vcpu-ubuntu-2204"
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v3
+
+      - uses: ./.github/actions/setup-go
+      - name: Run Tests
+        run: |
+          gotestsum --junitfile="gotests.xml" -- --tags="timing" -p=1 -run='_Timing/' ./...
+
+      - uses: ./.github/actions/upload-datadog
+        if: always()
+        with:
+          api-key: ${{ secrets.DATADOG_API_KEY }}

scaletest/agentconn/run_test.go

@@ -109,6 +109,7 @@ func Test_Runner(t *testing.T) {
 
 //nolint:paralleltest // Measures timing as part of the test.
 func Test_Runner_Timing(t *testing.T) {
+	testutil.SkipIfNotTiming(t)
 	//nolint:paralleltest
 	t.Run("Direct+Hold", func(t *testing.T) {
 		client, agentID := setupRunnerTest(t)