[Improvement] Use hideLocalCluster flag to determine whether a dataSourceId must be present

[DarshitChanpura]

At present, the dataSourceId schema validation for a route is lax in the sense that a dataSourceId when not present, it falls back to "Local Cluster".

This validation should be updated to check for hideLocalCluster flag. If the flag is set to false, then check if dataSourceId is present and a non-empty string.

[cwperks]

[Triage] @DarshitChanpura Should I assign this issue to you?