[lit] Fix tests on Windows

max-time.py:
Windows does not have a native `sleep` command, use `time.sleep()` in
Python instead.

max-failures.py:
The max-failure test reused the shtest-shell tes

[lit] Fix tests on Windows

max-time.py:
Windows does not have a native `sleep` command, use `time.sleep()` in
Python instead.

max-failures.py:
The max-failure test reused the shtest-shell test inputs instead of
defining its own "test domain". However, the output of this
shtest-shell "test domain" is slightly different on Windows, which now
bites us since we made the max-failures test stricter. Let's define
our own "max failures" test domain.

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