standalone heat: Retry removing the install directory
standalone heat: Retry removing the install directory

... in case rmdir failed because of EBUSY, to avoid immediate command
failure in case the directory has not yet been released after umount.

Closes-Bug: #1986742
Change-Id: I8d8e658a66f0fdd4992d34354bcfd583f9b366e5

openstack/python-tripleoclient