* Download the working msys64 and use it to compile 27
* Remove the cygwin detection override logic
* Only install Python interpreters in jobs running on winserver2016
* Fix the batch script substring check
* Increase the timeout for related jobs
* TIL that there is an allow list for Kokoro env vars
if the kokoro job times out and the bazel command is not done, it ends up in
weird test results ("Unevaluated targets") that are hard to interpret.
Setting the timeout for kokoro jobs high enough to create extra reserve
should help.
Lidi Zheng