Enable test_rref_timeout for Tensorpipe agent

[rohan-varma]

🚀 Feature

https://github.com/pytorch/pytorch/pull/38590/files is adding support for RRef timeouts, but the necessary error handling is not yet added to Tensorpipe agent. The test test_rref_timeout is disabled for tensorpipe in that PR, so we should add the necessary support to TP and enable this test and verify that RRef timeouts work appropriately.

cc @pietern @mrshenli @pritamdamania87 @zhaojuanmao @satgera @gqchen @aazzolini @rohan-varma @xush6528 @jjlilley @osalpekar @jiayisuse @lw @beauby

[lw]

I think this has been done in #39531