Update sql-vm-create-portal-quickstart.md

Removing reference to Azure Marketplace image for SQL Server on Linux as we are removing those to bring in script based deployment

Update rhel-high-availability-fencing-tutorial.md

Remove references to Azure Marketplace image for SQL Server on Linux VM.

Update ubuntu-high-availability-fencing-tutorial.md

Removing reference to the SQL Server based Azure VM images.

Update quickstart-install-connect-ubuntu.md

removing reference to Azure marketplace images

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Author: amitkh-msft