integration: clean up temp dir abstraction
integration: clean up temp dir abstraction

Signed-off-by: Chris Koch <cd2178739c1fb8f241acc6c7bd5abe02c150d7e5@google.com>

u-root/u-root,u-root/u-root,hugelgupf/u-root,hugelgupf/u-root,GanShun/u-root,GanShun/u-root,GanShun/u-root,u-root/u-root,hugelgupf/u-root,hugelgupf/u-root