unittests: increase timeouts and fix race in DiskSpaceAllocatorTest

Various unit tests have timeouts to allow the test to fail if it gets
stuck.  While such tests are short-lived and the existing timeouts work
fine for desktop environments, when testing under heavy load the thread
scheduling within the OS can lead to severe delays and the tests could
fail.  For this reason, the timeouts are bumped up to 1 minute.  Tests
should aim to complete easily within one second (number picked out of
the air), so one minute should allow at least 2 orders of magnitude
leeway.

This patch also removes two unnecessary assertions.  These assertions
add nothing against an existing, earlier test and introduce a race
condition for a possible failure mode.

The test in question has a race in attempting to ensure the testing
thread blocks.  This is hard to fix without rewriting the code being
tested and, since it doesn't affect the test result, the code is left
as-is.

Target: master
Patch: https://rb.dcache.org/r/7308/
Acked-by: Tigran Mkrtchyan
Requires-notes: no
Requires-book: no
Request: 2.10
Request: 2.9
Request: 2.8
Request: 2.7
Request: 2.6
(cherry picked from commit 3d622367d9f5b3cef03eeef869338a2c71cf3041)
pool: Fix xrootd vector read limits

Fixes a bug that caused problems with ROOT 6: dCache provided
too large limits for the readv_ior_max and readv_iov_max
properties.

Target: trunk
Request: 2.10
Request: 2.9
Request: 2.8
Request: 2.7
Request: 2.6
Ticket: http://rt.dcache.org/Ticket/Display.html?id=8461
Require-notes: ues
Require-book: no
Acked-by: Paul Millar <paul.millar@desy.de>
Patch: https://rb.dcache.org/r/7313/
(cherry picked from commit 92b36682cf3dd4aab14dab64ded6bf40e5660f4d)
(cherry picked from commit e7371f05769b410925178fd59f2923a6f8250fbf)