Splunk Add-on for VMware Metrics Indexes contains the indexes used by Splunk Add-on for VMware Metrics and was part of the build package till Splunk Add-on for VMware Metrics v4.2.0. In order to make the Splunk Add-on for VMware Metrics v4.2.0 SSAI-compatible, the package has been removed from the add-on package and published as an individual Splunkbase add-on.
The package ('SA-VMWIndex-inframon') present in this TA supplies the definition of indexes that are used by Splunk Add-on for VMware Metrics, Splunk Add-on for vCenter Logs, and Splunk Add-on for VMware ESXi Logs. See Install and Configure Splunk Add-on for VMware Metrics Indexes (Link: 'Install and Configure' section of Splunk Add-on for VMware Metrics Indexes) to see the installation instructions.