test-module.ps1 ignores local Az.Accounts even though its version is higher

`test-module.ps1` uses locally installed Az.Accounts if its version is higher than the embedded one, but it didn't and caused the test cases of Functions to fail.

To reproduce

```powershell
git checkout main
git reset --hard upstream/main
git checkout -b functions-update-stacks-may-2025-base

# generate code
autorest --reset
autorest --powershell --debug --verbose 3>&1 2>&1 > log.txt

# build module
.\build-module.ps1

# run tests
.\test-module.ps1 -Playback

Tests completed in 9.32s
Tests Passed: 0, Failed: 64, Skipped: 18, Pending: 0, Inconclusive: 0

PS C:\Users\x\code\azure-powershell\src\Functions\Functions.Autorest [68.08s]> gmo az.accounts -li

Directory: C:\Users\x\Documents\PowerShell\Modules

ModuleType Version PreRelease Name PSEdition ExportedCommands
---------- ------- ---------- ---- --------- ----------------
Script 4.2.0 Az.Accounts Core,Desk {Disable-AzDataCollection, Disable-AzContextAutosave, Enable-AzDataCollection, Enable-AzContextAutosave…}

Directory: C:\Program Files\WindowsPowerShell\Modules

ModuleType Version PreRelease Name PSEdition ExportedCommands
---------- ------- ---------- ---- --------- ----------------
Script 4.0.2 Az.Accounts Core,Desk {Disable-AzDataCollection, Disable-AzContextAutosave, Enable-AzDataCollection, Enable-AzContextAutosave…}

```

Mannually remove the one in .\generated\modules\Az.Accounts can workaround this problem.