xSQLServer: Fixed typos and the use of wrong parameters in unit tests

[johlju]

Pull Request (PR) description

• Changes to xSQLServer
  • Fixed typos and the use of wrong parameters in unit tests which was
    found after release of new version of Pester (issue xSQLServer: New Pester version released to PowerShell Gallery breaks tests #773).

This Pull Request (PR) fixes the following issues:
Fixes #773

Task list:

• Change details added to Unreleased section of CHANGELOG.md?
• Added/updated documentation, comment-based help and descriptions in .schema.mof files where appropriate?
• Examples appropriately updated?
• New/changed code adheres to Style Guidelines?
• Unit and (optional) Integration tests created/updated where possible?

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This change is 

[codecov-io]

Codecov Report

Merging #777 into dev will not change coverage.
The diff coverage is n/a.

@@         Coverage Diff         @@
##            dev   #777   +/-   ##
===================================
  Coverage    97%    97%           
===================================
  Files        30     30           
  Lines      3250   3250           
===================================
  Hits       3165   3165           
  Misses       85     85

[johlju]

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Reviewed 16 of 16 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

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