Enable disabled `AsyncProcessTests` Windows tests

[bkhouri]

Is it reproducible with SwiftPM command-line tools: swift build, swift test, swift package etc?

• Confirmed reproduction steps with SwiftPM CLI. The description text must include reproduction steps with either of command-line SwiftPM commands, swift build, swift test, swift package etc.

Description

There are a few AsyncProcessTests that are disabled on Windows. This issue is to track re-enabling those tests.

Expected behavior

The tests pass, or a skipped test references a more specific open GitHub issue

Actual behavior

When #8500 is merged, a few AsyncProcessTests remain disabled on Windows.

Steps to reproduce

n/a

Swift Package Manager version/commit hash

n/a

Swift & OS version (output of swift --version ; uname -a)

n/a