[BUG] waagent on AzureStack shows warnings mounting sr0 and "ProvisionGuestAgent not found" errors

WALinuxAgent on AzureStack shows warnings when mounting the DVD to copy `ovf-env.xml` and errors that the **ProvisionGuestAgent** configuration is not found. This seems to result in the network not coming up properly.

Here is the `sr0` mount warning and the **ProvisionGuestAgent** failure:

2019/04/10 16:11:27.856511 INFO Daemon Running default provisioning handler
2019/04/10 16:11:27.884842 INFO Daemon Copying ovf-env.xml
[28.445917] UDF-fs: warning (device sr0): udf_fill_super: No partition found (2)
2019/04/10 16:11:27.995593 INFO Daemon Successfully mounted dvd
2019/04/10 16:11:28.019821 ERROR Daemon Provisioning failed: [ProtocolError] Failed to validate OVF: ProvisionGuestAgent not found (28.52s)

Here are the issues seen afterward regarding the network issues:

2019/04/10 16:11:28.039656 INFO Daemon WireServer endpoint is not found. Rerun dhcp handler
2019/04/10 16:11:28.046580 INFO Daemon Test for route to 168.63.129.16
2019/04/10 16:11:28.047207 WARNING Daemon No route exists to 168.63.129.16
...
2019/04/10 16:11:28.396398 INFO Daemon WireServer is not responding. Reset endpoint
2019/04/10 16:11:28.396582 INFO Daemon Protocol endpoint not found: WireProtocol, [ProtocolError] WireProtocol endpoint is None
2019/04/10 16:11:28.399513 INFO Daemon Protocol endpoint not found: MetadataProtocol, [ProtocolError] 400 - GET:
+http://169.254.169.254/Microsoft.Compute/identity?api-version=2015-05-01-preview
...
2019/04/10 16:12:41.989732 INFO Daemon Retry detect protocols: retry=7
2019/04/10 16:12:52.000000 INFO Daemon WireServer endpoint is not found. Rerun dhcp handler
2019/04/10 16:12:53.611279 INFO Daemon Test for route to 168.63.129.16
2019/04/10 16:12:53.612217 WARNING Daemon No route exists to 168.63.129.16
2019/04/10 16:12:53.624136 INFO Daemon Send dhcp request
2019/04/10 16:12:53.624641 INFO Daemon Examine /proc/net/route for primary interface
2019/04/10 16:12:53.625178 INFO Daemon Primary interface is [eth0]
2019/04/10 16:12:53.644914 INFO Daemon Examine /proc/net/route for primary interface
2019/04/10 16:12:54.2[ 125.789501] sched: RT throttling activated
05429 INFO Daemon Primary interface is [eth0]
2019/04/10 16:13:04.239855 WARNING Daemon Failed to send DHCP request: [DhcpError] timed out

**Distro and WALinuxAgent details:**
- Distro and Version: Red Hat Enterprise Linux 7.6
- Running on AzureStack
- WALinuxAgent version 2.2.36

**Additional context**
This happens when creating a new image and uploading it to the AzureStack environment for provisioning. The Hyper-V instructions linked below are used.

https://docs.microsoft.com/en-us/azure/azure-stack/azure-stack-redhat-create-upload-vhd

Start with the linked Azure Stack Red Hat create/upload VHD instructions and reproduce provisioning with RHEL 7.6 and WALinuxAgent 2.2.36. Trace the logged DVD/OVF validation, WireServer detection, and DHCP failures; done means the image provisions without the ProvisionGuestAgent error and the network comes up.

Written by the indexing model from the issue text.