ci: remove unnused action secrets from system-tests [backport 3.16] (#14839)

Backport b6d846e from #14834 to 3.16.

## Description

These aren't needed or used anymore, so we can stop providing them.

## Testing

<!-- Describe your testing strategy or note what tests are included -->

## Risks

<!-- Note any risks associated with this change, or "None" if no risks
-->

## Additional Notes

<!-- Any other information that would be helpful for reviewers -->

Co-authored-by: Brett Langdon <[email protected]>

Author: dd-octo-sts[bot]

.github/workflows/system-tests.yml

@@ -35,8 +35,6 @@ jobs:
       TEST_LIBRARY: python
       WEBLOG_VARIANT: ${{ matrix.weblog-variant }}
       CMAKE_BUILD_PARALLEL_LEVEL: 12
-      SYSTEM_TESTS_AWS_ACCESS_KEY_ID: ${{ secrets.IDM_AWS_ACCESS_KEY_ID }}
-      SYSTEM_TESTS_AWS_SECRET_ACCESS_KEY: ${{ secrets.IDM_AWS_SECRET_ACCESS_KEY }}
     steps:
       - name: Install Dependencies
         run: sudo apt-get install -y patchelf
@@ -84,8 +82,6 @@ jobs:
       TEST_LIBRARY: python
       WEBLOG_VARIANT: ${{ matrix.weblog-variant }}
       CMAKE_BUILD_PARALLEL_LEVEL: 12
-      SYSTEM_TESTS_AWS_ACCESS_KEY_ID: ${{ secrets.IDM_AWS_ACCESS_KEY_ID }}
-      SYSTEM_TESTS_AWS_SECRET_ACCESS_KEY: ${{ secrets.IDM_AWS_SECRET_ACCESS_KEY }}
     steps:
 
       - name: Checkout system tests