Various small fixes to VimConnectMixin without the broker

[agrare]

1. Make sure to disconnect after raw_connect to verify credentials
2. Clear the connection and reconnect if the conn isn't alive
3. Don't rescue broker exception if we're not using the broker

#484

[miq-bot]

Checked commits agrare/manageiq-providers-vmware@e814568~...a53ba3b with ruby 2.5.5, rubocop 0.69.0, haml-lint 0.20.0, and yamllint 1.10.0
1 file checked, 1 offense detected

app/models/manageiq/providers/vmware/infra_manager/vim_connect_mixin.rb

• ❗ - Line 56, Col 9 - Style/RescueModifier - Avoid using rescue in its modifier form.