selftests/vm/run_vmtests: Polish output text

Few currently running test notification messages from run_vmtests output
have mismatched highlight lines.  This commit fixes them to fit in
length.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>