Hi,
The setting is non-existent in 6.7, you have to create it either via PowerCLI or by using the vCenter GUI. To add the setting to your vCenter advanced settings you can run the following command from PowerCLI -- New-AdvancedSetting -Entity <your vcenter server name> -Name config.vpxd.hostPasswordLength -Value 32
then, you can check the setting by running: Get-AdvancedSetting -Entity <your vcenter server name> -Name config.vpxd.hostPasswordLength | Set-AdvancedSetting -Value 32
Note: take <> off the command.
Note: that the value is set to 32, that is what the stig calls for so you can mark that control as 'Not a Finding' on your stig.