Fix the flakiness of 2391-virtual-thread-sleeps

Use the java thread id instead because the id shouldn't be re-used
for the next thread.

Flag: TEST_ONLY
Bug: 425929823
Test: 2391-virtual-thread-sleeps
Change-Id: Ief2cb133c12e32319bd876d32239dd92a47a38e0
1 file changed