Fix unresponsive Save button while editing VM

[hstastna]

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1610466

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What:
Save button in editing screen of VM is not responsive: it remains enabled even if no change was made (of if there is nothing to save).

Why:
The problem was that if changed variable was set to false, no update for Save button visibility was made. That's ok BUT what if Save button was enabled before and needs to be disabled now? This situation was not implemented in the code and it is simply fixed by removing condition if changed which is unnecessary and caused the bug.

Steps to Reproduce:

1. Go to Compute > Infra > VMs (or to any page with VMs list screen)
2. Click on some VM or check the checkbox
3. Configuration > Edit Selected item/Edit this VM
4. Make some change(s) in Basic Information or Parent VM Selection section,
   for example enter something in Description form
   => Save button enables
5. Remove all of your changes
   => Save button remains enabled!

Right after starting editing of a chosen VM:

Making some change of a VM:

Before: (after removing changes for VM)

After:

[hstastna]

@miq-bot add_label bug, gaprindashvili/yes

[hstastna]

@h-kataria @mzazrivec This is a simple fix for Save button. Could you, please, check it? Thanks! 🎇

[miq-bot]

Checked commit hstastna@3efbfae with ruby 2.3.3, rubocop 0.52.1, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 0 offenses detected
Everything looks fine. 🍰