Fix flaky one_spawn_single_tasks_works__thread_id_is_different_than_main test

[rafal-ch]

Link to failed build: https://github.com/FuelLabs/fuel-core/actions/runs/11970991093/job/33374927120?pr=2383

Output:

--- STDOUT:              fuel-core-services async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main ---

running 1 test
test async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main ... FAILED

failures:

failures:
    async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main

test result: FAILED. 0 passed; 1 failed; 0 ignored; 0 measured; 26 filtered out; finished in 1.04s


--- STDERR:              fuel-core-services async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main ---
thread 'async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main' panicked at crates/services/src/async_processor.rs:179:9:
assertion `left == right` failed
  left: 8
 right: 10
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

  Cancelling due to test failure: 3 tests still running
        PASS [   0.007s] fuel-core-services service::tests::double_await_stop_works
        PASS [   1.005s] fuel-core-services async_processor::tests::second_spawn_works_when_first_is_finished
        PASS [  11.010s] fuel-core-services async_processor::tests::executes_10_tasks_for_10_seconds_with_one_thread
        SLOW [> 60.000s] fuel-core-e2e-client::integration_tests works_in_multinode_local_env
        PASS [  75.317s] fuel-core-e2e-client::integration_tests works_in_multinode_local_env
------------
     Summary [  85.922s] 692/1155 tests run: 691 passed (1 slow), 1 failed, 4 skipped
        FAIL [   1.044s] fuel-core-services async_processor::tests::one_spawn_single_tasks_works__thread_id_is_different_than_main
warning: 463/1155 tests were not run due to test failure (run with --no-fail-fast to run all tests)
error: test run failed
Error: Process completed with exit code 100.

[rafal-ch]

Another instance: https://github.com/FuelLabs/fuel-core/actions/runs/12137093721/job/33839618712?pr=2463