fix(test): remove mandatory-param invocation tests that hang PS 5.1

PS 5.1 prompts interactively for mandatory parameters instead of
throwing, causing CI to hang indefinitely. Replace invocation-based
tests with attribute-based IsMandatory checks where duplicates exist,
or convert to attribute checks where they don't.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

tests/PSProxmoxVE.Tests/Containers/ContainerLifecycle.Tests.ps1

@@ -58,10 +58,6 @@ Describe 'New-PveContainer' {
             $isMandatory | Should -Not -BeNullOrEmpty
         }
 
-        It 'Should throw when Node is omitted' {
-            Skip-IfMissing 'New-PveContainer'
-            { New-PveContainer -ErrorAction Stop } | Should -Throw
-        }
     }
 
     Context 'Optional parameters' {