fix(ci): remove duplicate wit- prefix from archivista auth header

secret already contains wit- prefix, don't add it again.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: cole-rgb

.github/workflows/test-staging-cilock.yaml

@@ -59,5 +59,5 @@ jobs:
             --timestamp-servers "$STAGING_URL/api/v1/timestamp" \
             --enable-archivista \
             --archivista-server "$STAGING_URL/archivista" \
-            --archivista-headers "Authorization: wit-${{ secrets.TESTIFYSEC_STAGING_API_KEY }}" \
+            --archivista-headers "Authorization: ${{ secrets.TESTIFYSEC_STAGING_API_KEY }}" \
             -- echo "testing cilock CLI against staging"