Setup fails when using EC2 instance

[Manno15]

When trying to set up an Ec2 instance, I received:

AttributeError: 'Ec2Cluster' object has no attribute 'add_specialized_configs'

This appears to be related to a recent change, #395, where self.add_specialized_configs(hosts_file) was added to existing.py. Without this line, the setup runs as expected.

[arvindshmicrosoft]

Sorry for the trouble @Manno15 - yes, this line should ideally have been under a conditional check for Azure clusters. @karthick-rn would you be able to address this?

[karthick-rn]

@Manno15 Hi, I have submitted #410 to fix this. Thanks for letting us know.

[karthick-rn]

Merged the PR