SqlRSSecureConnectionLevel: Remove parameter SQLAdminCredential

[johlju]

Details of the scenario you tried and the problem that is occurring:
For resource xSQLServerRSConfig it was decided to remove SQLAdminCredential in favor for using PsDscunAsCredential. This decision was made because the module will move to WMF 5.x as the minimum supporter version of WMF.

So this resource xSQLServerRSSecureConnectionLevel should also remove the need to have the parameter SQLAdminCredential.

The DSC configuration that is using the resource (as detailed as possible):
n/a

Version of the Operating System, SQL Server and PowerShell the DSC Target Node is running:
n/a

What module (SqlServer or SQLPS) and which version of the module the DSC Target Node is running:
n/a

Version of the DSC module you're using, or 'dev' if you're using current dev branch:
Dev

[johlju]

If issue #587 is accepted, then this issue is obsolete.