Remove default variables from Defender test configs

[schrolla]

🗣 Description

Remove default variables from Defender test configs. In particular, the OPAPath variable is set to the old . default which causes testing to fail if the tester does not have the OPA executable in their current directory. Removing the variable from the test configuration causes it to default to the correct value of ${env.USERPROFILE}\.scubagear\Tools instead.

💭 Motivation and context

Resolves a bug that can impact the ability to run automated testing against Defender settings and decreases the size of the test configurations to just the values necessary for a given test.

Closes #992

🧪 Testing

To test that the update configurations work as intended, execute automated testing with the following script and the appropriate test tenant and service principal details set as needed.

1. Run the following from ScubaGear directory, replacing values based on environment under test:

$TestContainers = New-PesterContainer -Path "Testing/Functional/Products" -Data @{ Thumbprint = <CERT_THUMBPRINT>; TenantDomain = "<TEST_TENANT_DOMAIN_HERE>"; TenantDisplayName = "<TENANT_NAME>"; AppId = "<APP_ID>"; ProductName = "defender"; M365Environment = "gcc"}

$PesterConfig = @{
    Run = @{
        Container = $TestContainers
    }
    Filter = @{
        Tag = @("MS.DEFENDER.2.[123]v1")
    }
    Output = @{
        Verbosity = 'Detailed'
    }
    Debug = @{
        ShowFullErrors = $false
        WriteDebugMessages = $true
    }
}
 
$Config = New-PesterConfiguration -Hashtable $PesterConfig
Invoke-Pester -Configuration $Config

Running these commands should not result in the errors listed in the screenshot in #992 which reference a failure due to an inability to find the OPA executable in the current directory. Other errors with tests may occur depending on the setup, but are not related to this config file.

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✅ Post-merge checklist

• Feature branch deleted after merge to clean up repository.
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[rgbrow1949]

The opapath fix worked as intended. Tested it by putting the opa exe in a different place in the hierarchy. This branch needs a rebase but everything else is good to go.

[buidav]

Took way longer than expected to test Defender.
Seems like a simple removal of mandatory variable specification because of #761 and path changes in #677
LGTM.

[schrolla]

@nanda-katikaneni This PR is ready for merge. All tests passing, approved, and rebased to latest main.