ci: drop dead "load jwt in the environment just before exiting the job" code

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/31855>

.gitlab-ci.yml

@@ -114,13 +114,6 @@ default:
     # Work around https://gitlab.com/gitlab-org/gitlab/-/issues/20338
     - find -name '*.log' -exec mv {} {}.txt \;
 
-    - >
-      set +x
-
-      test -e "${S3_JWT_FILE}" &&
-      export S3_JWT="$(<${S3_JWT_FILE})" &&
-      rm "${S3_JWT_FILE}"
-
   # Retry when job fails. Failed jobs can be found in the Mesa CI Daily Reports:
   # https://gitlab.freedesktop.org/mesa/mesa/-/issues/?sort=created_date&state=opened&label_name%5B%5D=CI%20daily
   retry: