[GPU] Fix unused lambda capture 'this' in random_uniform_kernel_ref (#34189)
### Details:
- SetDefault is a free function, not a member method, so capturing
'this' in the update_dispatch_data_func lambda is unnecessary. Remove it
to fix -Werror,-Wunused-lambda-capture error when building with
-DENABLE_FUZZING=ON (clang + sanitizer flags).
### Tickets:
- 181419