[llvm] [NFC][bolt][test] Change '|&' to '2>&1 |' for lit internal shell support (PR #102402)

[Paul Kirth via llvm-commits]

ilovepi wrote:

> Hi. I'm not too deep in lit internal shell thematics, but it won't prevent on creating new tests with 2>&1 syntax. Is there any reason that 2>&1 is not supported by lit shell? Maybe it should be fixed there?

`2>&1` is supported. This change removes the bashism `|&`, and replaces it w/ `2>&1`, unless I've misunderstood.

https://github.com/llvm/llvm-project/pull/102402