fix: populate GIT_COMMIT_SHA envvar in containers built in CI (#7001)

Signed-off-by: Harrison King Saturley-Hall <hsaturleyhal@nvidia.com>

.github/workflows/build-test-distribute-flavor.yml

@@ -277,6 +277,8 @@ jobs:
           extra_tags: ${{ steps.extra-tags.outputs.tags }}
           push_image: ${{ inputs.push_image }}
           no_load: ${{ inputs.no_load }}
+          extra_build_args: |
+            DYNAMO_COMMIT_SHA=${{ github.sha }}
       - name: Show summary
         shell: bash
         if: ${{ inputs.push_image && inputs.show_summary }}