Attempt to fix the `rpc_bind.py` flakiness:
```
Traceback (most recent call last):
File "/work/test/functional/test_framework/test_framework.py", line
120, in main
self.run_test()
File "/work/test/functional/rpc_bind.py", line 136, in run_test
self._run_nonloopback_tests()
File "/work/test/functional/rpc_bind.py", line 171, in
_run_nonloopback_tests
[(self.non_loopback_ip, self.defaultport)])
File "/work/test/functional/rpc_bind.py", line 72, in run_bind_test
assert_equal(set(get_bind_addrs(pid)), set(expected))
File "/work/test/functional/test_framework/netutil.py", line 87, in
get_bind_addrs
inodes = get_socket_inodes(pid)
File "/work/test/functional/test_framework/netutil.py", line 37, in
get_socket_inodes
target = os.readlink(os.path.join(base, item))
FileNotFoundError: [Errno 2] No such file or directory:
'/proc/7775/fd/26'
```