LCORE-1724: add credential debug logging for STS troubleshooting

Print length and hash of AWS creds in both assume-role and create
steps to detect truncation or corruption during param passing.

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

Author: are-ces

.tekton/integration-tests/pipeline/lightspeed-stack-rhelai-test.yaml

@@ -81,6 +81,11 @@ spec:
               open('$(results.aws-session-token.path)', 'w').write(c['SessionToken'])
               "
               echo "[sts] Temporary credentials obtained (valid 4h)."
+              echo "[sts] Key ID length: $(wc -c < $(results.aws-access-key-id.path))"
+              echo "[sts] Secret length: $(wc -c < $(results.aws-secret-access-key.path))"
+              echo "[sts] Token length: $(wc -c < $(results.aws-session-token.path))"
+              echo "[sts] Key ID hash: $(md5sum $(results.aws-access-key-id.path) | cut -d' ' -f1)"
+              echo "[sts] Token hash: $(md5sum $(results.aws-session-token.path) | cut -d' ' -f1)"
 
     # ── RHEL AI provisioning (MAPT) ──
     - name: provision-rhelai
@@ -139,6 +144,11 @@ spec:
               export AWS_ACCESS_KEY_ID="$(params.aws-access-key-id)"
               export AWS_SECRET_ACCESS_KEY="$(params.aws-secret-access-key)"
               export AWS_SESSION_TOKEN="$(params.aws-session-token)"
+              echo "[mapt] Key ID length: ${#AWS_ACCESS_KEY_ID}"
+              echo "[mapt] Secret length: ${#AWS_SECRET_ACCESS_KEY}"
+              echo "[mapt] Token length: ${#AWS_SESSION_TOKEN}"
+              echo "[mapt] Key ID hash: $(echo -n "$AWS_ACCESS_KEY_ID" | md5sum | cut -d' ' -f1)"
+              echo "[mapt] Token hash: $(echo -n "$AWS_SESSION_TOKEN" | md5sum | cut -d' ' -f1)"
               BUCKET=$(cat /opt/aws-credentials/S3_BUCKET)
               RUN_ID="$(context.pipelineRun.name)"
               HF_TOKEN=$(cat /opt/aws-credentials/HUGGING_FACE_HUB_TOKEN)