Fix shtest-timeout test harder

Don't produce or expect any output from the infinite looping test -
doing so is a recipe for racey flakyness without a longer timeout to
ensure the output is received first, even though that doesn't seem
integral/important to the test. Instead have a plain, no output infinite
loop and check that that is caught and handled.

If for some reason the output is valuable for test coverage - the
timeout should be increased from 1 second to give the process time to
output the text, flush, and for that text to be received and buffered
before the test is timed out.