fix(scripts): satisfy PSScriptAnalyzer (lint gate)

- Remove-Securely: suppress PSUseShouldProcessForStateChangingFunctions
  (internal best-effort shred; ShouldProcess prompts are undesirable)
  + add [CmdletBinding()].
- Replace the two empty catch blocks (Set-CIGuestCredential.ps1,
  Test-CIGuestWinRM.ps1) with Write-Verbose so PSAvoidUsingEmptyCatchBlock
  is satisfied while keeping best-effort behavior.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

scripts/Set-CIGuestCredential.ps1

@@ -115,6 +115,11 @@ function Invoke-AsSystem {
 
 # --- Harden + shred helper for the transient secret file ------------------
 function Remove-Securely {
+    # Best-effort cleanup helper; ShouldProcess prompting is undesirable
+    # for an internal shred-and-delete of our own temp file.
+    [Diagnostics.CodeAnalysis.SuppressMessageAttribute(
+        'PSUseShouldProcessForStateChangingFunctions', '')]
+    [CmdletBinding()]
     param([Parameter(Mandatory)] [string] $Path)
     if (-not (Test-Path -LiteralPath $Path)) { return }
     try {
@@ -124,7 +129,9 @@ function Remove-Securely {
             [Security.Cryptography.RandomNumberGenerator]::Create().GetBytes($rnd)
             [IO.File]::WriteAllBytes($Path, $rnd)
         }
-    } catch { }
+    } catch {
+        Write-Verbose "secure overwrite failed (continuing to delete): $_"
+    }
     Remove-Item -LiteralPath $Path -Force -ErrorAction SilentlyContinue
 }