[BUG] "WARNING mounting DVD failed" when provisioning agent crashes and is restarted

**Describe the bug**
When the provisioning agent starts, its first action is to capture the ovf.xml file. The specific sequence of operations:

- mount the dvd
- read the ovf.xml file from the dvd
- write the (redacted) ovf.xml file to disk
- umount the dvd
- eject the dvd

This is a non-idempotent sequence of operations. If the provisioning agent crashes before completing provisioning, it gets restarted, but the attempt to mount the dvd fails because it has been ejected.

The "eject the dvd" operation should be deferred until after provisioning is complete.

**Distro and WALinuxAgent details (please complete the following information):**
- CemtOS 7.5 and earlier
- WALinuxAgent version is unknown but older than 2.2.34

**Additional context**
Unfortunately, the "cannot mount dvd" handler cannot just use the copy of ovf.xml written to disk by the first (failed) instance of the provisioning agent because the agent password has been redacted from the copy written to disk.

Trace the provisioning agent startup flow that mounts the DVD, reads ovf.xml, writes the redacted copy, unmounts, and ejects the media. Verify restart behavior and preserve access to the unredacted source needed for provisioning; done means DVD ejection is deferred until provisioning completes and a crash/restart no longer produces the mount warning.

Written by the indexing model from the issue text.