With 87ddc76, value column in cloud.cluster_details has been made non-nullable.
While adding a cluster (especially VMware), addCluster API can be called without username password. Username and password are updated in cluster details entry later after successful discovery.
This PR stores an empty string instead of a null value when initial cluster entry is made in the DB.
Signed-off-by: Abhishek Kumar <abhishek.mrt22@gmail.com>