The goal of this issue is to enable by default the Heart beat timer feature, which lets Piwik JavaScript tracking client send ping requests every N second. By enabling this feature by default we will provide more accurate accurate time on site and time on page.

Steps;

• in the JavaScript tracking code, write enableHeartBeatTimer just like we write enableLinkTracking
• Requires a mechanism where by default, ping frequencies will go down so it won't overload servers, eg. Allow JS tracker to change heart beat wait interval exponentially #8213

Follows up #8069 #2041 #8218 #8223