fix(meeting join): fail better when we can't find locus join meeting url

[lismith2-cisco]

COMPLETES # jira-eng-gpk2.cisco.com/jira/browse/SPARK-813470

This pull request addresses

There was a particular scenario where we were not getting enough information to make a locus join meeting url
We ended up using the url "?alternateRedirect=true" which made a POST to the current URL instead of Locus, and the failure reason was unclear.

by making the following changes

Throw an error if the locus join meeting url is empty. The actual bug is fixed in web client.

Change Type

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Tooling change
• Internal code refactor

The following scenarios were tested

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