test: Slightly improve names of test directories

Signed-off-by: Magnus Malm <magnusmalm@gmail.com>

test/test-root/.gitignore

@@ -0,0 +1,32 @@
+/bin/busybox-x86_64
+/bin/cat
+/bin/cp
+/bin/date
+/bin/echo
+/bin/env
+/bin/find
+/bin/initctl
+/bin/kill
+/bin/ls
+/bin/mkdir
+/bin/mkfifo
+/bin/mknod
+/bin/mount
+/bin/pgrep
+/bin/printf
+/bin/ps
+/bin/rm
+/bin/sh
+/bin/sleep
+/bin/top
+/bin/touch
+/dev
+/etc
+/lib64
+/proc
+/sbin
+/sys
+/test_assets
+/tmp
+/usr
+/var