Add option to skip mount of ConfigDrive

##### ISSUE TYPE

* Enhancement Request

##### COMPONENT NAME

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Backend
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##### CLOUDSTACK VERSION

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4.19.1.2
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##### CONFIGURATION

N/A

##### OS / ENVIRONMENT

Ubuntu 22 for Managemente
KVM with Rocky Linux for hypervisor

##### SUMMARY

HI team, I configured a L2 network offering with support for ConfigDrive, becasue i need to use cloudinit to do some tasks.
As per documentation, in this configuration, an iso will be created with ConfigDrive and attached as cdrom to instance.
Moreover with option we can decide to store it on primary or secondary storage.

However, this happen everytime I use at least one network where ConfigDrive is enabled and i don't find a way to "disable" this behaviour apart choice a network with different Offering.

It will be very usefull have a machine settings that can allow us to "disable" mounting the iso, for example after first deployment we can set it ad avoid attach or buil the iso.

##### STEPS TO REPRODUCE

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Create aL2 network offering with Userdata flagged
Create a VM with/without user data
Iso is attached to the vm and mounted (as default) to secondary storage
Remove network with this Network offering
Attach a network with netwokr offering without userdata
VM will not have attached the iso, iso is deleted on secondary
~~~

##### EXPECTED RESULTS

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Add a settings to disable the usage of userdata to vm specific
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##### ACTUAL RESULTS

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No way to disable userdata if is enabled on Network offering
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I think that one pice of code to be modified is this function:
https://github.com/apache/cloudstack/blob/019f2c60ceb7a7c15c670a98280bd5764a5fcf5b/server/src/main/java/com/cloud/network/element/ConfigDriveNetworkElement.java#L770-L793

As per system VM, we can add an option to avoid the configuration of ConfigDrive with vm settings.

What do you think team?

Start by reading ConfigDriveNetworkElement.java at the linked function around lines 770-793, then trace how VM-specific settings and ConfigDrive attachment are represented. Done means the issue’s proposed per-VM option can prevent ConfigDrive ISO creation or attachment while preserving the current network-offering behavior when the option is not used.

Written by the indexing model from the issue text.