expose bucket name (#3900)

<!-- PR description-->

Export Bucket name for CI Nightly test.

#### Does this PR need a docs update or release note?

- [x] ⛔ No

#### Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 💻 CI/Deployment

#### Issue(s)

<!-- Can reference multiple issues. Use one of the following "magic words" - "closes, fixes" to auto-close the Github issue. -->
* #<issue>

#### Test Plan

<!-- How will this be tested prior to merging.-->
- [ ] 💪 Manual
- [ ] ⚡ Unit test
- [x] 💚 E2E

.github/workflows/nightly_test.yml

@@ -94,6 +94,7 @@ jobs:
           CORSO_PASSPHRASE: ${{ secrets.INTEGRATION_TEST_CORSO_PASSPHRASE }}
           CORSO_LOG_FILE: ${{ github.workspace }}/testlog/run-nightly.log
           LOG_GRAPH_REQUESTS: true
+          S3_BUCKET: ${{ secrets.CI_TESTS_S3_BUCKET }}
         run: |
           set -euo pipefail
           go test       \