[SQL Migration] Bug fixes & Validations.

[stuti149]

1.The targetSelectionPage currently has a IaaS extension mode check for SQL VM targets. This check is no longer needed and is removed.
The SQLVM team has asked that this validation check be removed as it no longer applies. The behavior was observed during a customer call for the following incident:
https://portal.microsofticm.com/imp/v3/incidents/details/429943675/home

[coveralls]

Pull Request Test Coverage Report for Build 6939321071

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 1 unchanged line in 1 file lost coverage.
• Overall coverage decreased (-0.001%) to 41.568%

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Files with Coverage Reduction	New Missed Lines	%
extensions/notebook/src/dialog/configurePython/configurePythonWizard.ts	1	46.46%

Totals
Change from base Build 6937690638:	-0.001%
Covered Lines:	30790
Relevant Lines:	69372

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💛 - Coveralls