fix: correctly set cluster_id field in datasource ovh_dbaas_logs_cluster

[amstuta]

Description

When not defined in the configuration, the field cluster_id of datasource ovh_dbaas_logs_cluster was not set.

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (improve existing resource(s) or datasource(s))
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update

How Has This Been Tested?

• Test A: make testacc TESTARGS="-run TestAccDataSourceDbaasLogsCluster"
• Test B: make testacc TESTARGS="-run TestAccDataSourceDbaasLogsClusterDefault"