LU-13740 tests: improve sanity-sec test_45

LU-13740 tests: improve sanity-sec test_45

Improve sanity-sec test_45 by referencing the entire mmap-ed region
thanks to multiop.
Also make sure encryption tests are passing on newly supported
Ubuntu 20.04 distro.

Test-Parameters: trivial
Test-Parameters: testlist=sanity-sec envdefinitions=ONLY="36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 52 53 54" clientdistro=ubuntu2004 fstype=ldiskfs mdscount=2 mdtcount=4
Test-Parameters: testlist=sanity-sec envdefinitions=ONLY="36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 52 53 54" clientdistro=ubuntu2004 fstype=zfs mdscount=2 mdtcount=4
Test-Parameters: testlist=sanity-sec envdefinitions=ONLY="36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 52 53 54" clientdistro=el8.1 fstype=ldiskfs mdscount=2 mdtcount=4
Test-Parameters: testlist=sanity-sec envdefinitions=ONLY="36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 52 53 54" clientdistro=el8.1 fstype=zfs mdscount=2 mdtcount=4
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I983b6bf94d9f51486fd6b688267af46ed4188a98
Reviewed-on: https://review.whamcloud.com/40146
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>