Fix PartnerServerName check in GetAzureSqlDatabaseReplicationLink.cs

[alecbain]

Description

PartnerServerName (an optional parameter) is currently checking invocation by examining the value of the variable PartnerServerName instead of string literal "PartnerServerName". When invoking the cmdlet, it yields unexpected behavior as check never passes and it invokes as if PartnerServerName parameter was not passed.

Added double quotes around PartnerServerName to check for key.

Checklist

• I have read the Submitting Changes section of CONTRIBUTING.md
• The title of the PR is clear and informative
• The appropriate ChangeLog.md file(s) has been updated:
  • For any service, the ChangeLog.md file can be found at src/{{SERVICE}}/{{SERVICE}}/ChangeLog.md
  • A snippet outlining the change(s) made in the PR should be written under the ## Upcoming Release header -- no new version header should be added
• The PR does not introduce breaking changes
• If applicable, the changes made in the PR have proper test coverage
• For public API changes to cmdlets:
  • a cmdlet design review was approved for the changes in this repository (Microsoft internal only)
  • the markdown help files have been regenerated using the commands listed here

[isra-fel]

LGTM

[isra-fel]

/azp run azure-powershell - windows-powershell

[azure-pipelines]

Azure Pipelines successfully started running 1 pipeline(s).