test: ./tests/bugs/posix/bug-1651445.t is continuous failing during running test suite

[mohit84]

The ./tests/bugs/posix/bug-1651445.t is getting failed continuously while running test suite. The test case is failing after reaching a situation while brick is throwing an error and after cleanup, the data as the test case is trying to create a file it is failing.The file creation is failing because the flag (disk_space_full) is reset after every 5s by a thread posix_ctx_disk_thread_proc.

Solution: After cleanup data wait for 5s to reset the flag. Earlier the test case did the same but it was changed by the patch(https://github.com/gluster/glusterfs/pull/3637).