chore(ci): multiple integration tests per shard in CI (#3789)

Initially three tests per shard.

.github/workflows/ci.yml

@@ -255,7 +255,7 @@ jobs:
         run: |
           set -euo pipefail
           # shellcheck disable=SC2046
-          echo "matrix={\"test\":$(jq -c -n '$ARGS.positional' --args $(git grep -l '^//go:build integration' | xargs grep '^func Test' | awk '{print $2}' | cut -d'(' -f1))}" >> "$GITHUB_OUTPUT"
+          echo "matrix={\"test\":$(jq -c -n '$ARGS.positional' --args $(git grep -l '^//go:build integration' | xargs grep '^func Test' | awk '{print $2}' | cut -d'(' -f1 | paste -d '|' - - - | sed 's/|*$//'))}" >> "$GITHUB_OUTPUT"
   integration-run:
     name: Integration Test
     # if: github.event_name != 'pull_request' || github.event.action == 'enqueued' || contains( github.event.pull_request.labels.*.name, 'run-all')