Bug memory tab with dynamic memory missing url

[cocoon]

Describe the bug
Reported in the forum here:
https://xcp-ng.org/forum/topic/2804/yum-upgrade-8-0-to-8-1-vm-memory-error/

looks like a bug introduced by removing the Citrix-urls:
b2201f6#diff-07eabd7f8066c4f11a4c37b01b68cd39L192

root cause might be here:
https://github.com/xcp-ng/xenadmin/blob/development/XenAdmin/TabPages/BallooningPage.cs#L468

just compiled a build to try to see if commenting this will fix the error.

To Reproduce
Steps to reproduce the behavior:
https://xcp-ng.org/forum/topic/2804/yum-upgrade-8-0-to-8-1-vm-memory-error/

Expected behavior
No error, banner shoudl show that it is deprecated

Screenshots / Logfiles
If applicable, add screenshots / logfiles to help explain your problem.

Hard-/Software involved:
.

Additional context
.

[cocoon]

Confirmed:
commenting this line:
https://github.com/xcp-ng/xenadmin/blob/development/XenAdmin/TabPages/BallooningPage.cs#L468

removes the error but the "Details"-Link then does nothing.

So I think it would be better to provide an own DEPRECATION_URL or the previous one.

[borzel]

Hmm.. can you analyse to what that url should lead to? A webpage or some sort of data?

[cocoon]

I "think" it would be this:
https://docs.citrix.com/en-us/citrix-hypervisor/whats-new/removed-features.html

but I can confirm this with the other client.

Update: confirmed, this page opens.

[borzel]

I change the DEPRECATION_URL to https://github.com/xcp-ng/xcp/wiki/XCP-ng-8.1-Release-Notes