Fix port allocation race condition for elastic test (#65149)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/65149
Fixes #64789
There is a race condition between when the free port is acquired to when it is used to create the store in which it may have been used. Since this test only tests that timeout is triggered for tcpstore, we can bind to any port on tcpstore creation.
This only affects the test on the server (since that is where the port is used), but I changed both tests for clarity
cc pietern mrshenli pritamdamania87 zhaojuanmao satgera rohan-varma gqchen aazzolini osalpekar jiayisuse SciPioneer H-Huang cbalioglu gcramer23
Test Plan: Imported from OSS
Reviewed By: mrshenli
Differential Revision: D30993166
Pulled By: H-Huang
fbshipit-source-id: eac4f28d641ac87c4ebee89df83f90955144f2f1
