Nova cells support introduced a slight regression that triggers
odd behaviour when we tried switching to Apache (httpd) [1].
Bootstrap no longer applied permissions recursively to all log
files, creating a discrepancy between normal and bootstrap runs
and also Nova and other services such as Cinder (regarding
bootstrap logging).

This patch fixes it.

Backport to Train.

Not creating reno nor a bug record because it does not affect
any current standard usage in any currently known way.

Note this only really hides (standardizes?) the global issue that
we don't control file permissions on newly created files too well.

[1] https://review.opendev.org/724793

Change-Id: I35e9924ccede5edd2e1307043379aba944725143
Needed-By: https://review.opendev.org/724793