TEST/FLUSH: Fix the test in case the transport send always succeeds.
TEST/FLUSH: Fix the test in case the transport send always succeeds.

+ When the test raches timeout, need to count the send as successful.
+ Make the test run faster on valgrind by not waiting for specific time
  period during progress, and letting other threads make progress,

sergsagal1/ucx_rocm,shssf/ucx,sergsagal1/ucx_rocm,sergsagal1/ucx_rocm,shssf/ucx,shssf/ucx