LU-14298 tests: fix sanity-sec test_44 for aarch64 client

LU-14298 tests: fix sanity-sec test_44 for aarch64 client

PAGE_SIZE on aarch64 client is 64KB instead of 4KB, so sizes of IOs
performed in sanity-sec test_44 must be adapted.

Test-Parameters: testgroup=review-ldiskfs-arm env=ONLY=44 clientdistro=el8.3 serverdistro=el8.3
Signed-off-by: Sebastien Buisson <sbuisson@ddn.com>
Change-Id: I3764a75f6df871d71d751764627ed618bedf8e0b
Reviewed-on: https://review.whamcloud.com/41146
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Tested-by: Andreas Dilger <adilger@whamcloud.com>