alternator-test: increase timeout in tracing test
alternator-test: increase timeout in tracing test

Our test for tracing Alternator requests can't be sure when tracing a request
finished, because tracing is asynchronous and has no official ending signal.
So before we can conclude that tracing failed, we need to wait until a
timeout, which in the current code was roughly 6.4 seconds (the timeout
logic is unnecessarily convoluted, but to make a long story short it has
exponential sleeps starting with 0.1 second and ending with 3.2 seconds,
totaling 6.4 seconds).

It turns out that sporadically, in test runs on overcommitted test machines
with the very slow debug build, we fail this test with this timeout.
So this patch increases the timeout to 51.2 seconds. It should be more
than enough for everyone. Famous last words :-)

Signed-off-by: Nadav Har'El <625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>
Message-Id: <20210204151554.582260-1-625169824b719df98706d88646d0aae6f368ae4d@scylladb.com>

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