test: fix TEST-50-DISSECT under sanitizers

test: fix TEST-50-DISSECT under sanitizers

This test would normally get stuck when trying to mount the verity image
due to:

systemd-udevd[299]: dm-0: '/usr/sbin/dmsetup udevflags 6293812'(err) '==371==ASan runtime does not come first in initial library list; you should either link runtime to your application or manually preload it with LD_PRELOAD.'
systemd-udevd[299]: dm-0: Process '/usr/sbin/dmsetup udevflags 6293812' failed with exit code 1
...
systemd-udevd[299]: dm-0: '/usr/sbin/dmsetup udevcomplete 6293812'(err) '==372==ASan runtime does not come first in initial library list; you should either link runtime to your application or manually preload it with LD_PRELOAD.'
systemd-udevd[299]: dm-0: Process '/usr/sbin/dmsetup udevcomplete 6293812' failed with exit code 1.
systemd-udevd[299]: dm-0: Command "/usr/sbin/dmsetup udevcomplete 6293812" returned 1 (error), ignoring.

so let's add a simple udev rule which sets $LD_PRELOAD for the block
subsystem.

Also, install the ASan library along with necessary dependencies into
the verity minimal image, to get rid of the annoying (yet harmless)
errors about missing library from $LD_LIBRARY.