[Dashboard] Remove defer below fold setting

[ThomThomson]

Problem

The defer loading panels below the fold setting adds some complexity to the Dashboard application, is currently in a non-operational state, and was never made generally available. We should remove this setting

[elasticmachine]

Pinging @elastic/kibana-presentation (Team:Presentation)

[andremacola]

Removing doesn't make sense. In large and heavy dashboards and with high data volume, this considerably helps with loading time and prevents the execution of dozens of queries simultaneously.

Unless there is some scheme for sequential execution of widgets. If I don't use this above the fold option, several query errors occur in Kibana, especially over long date ranges.

More context here: #170121

[ThomThomson]

@andremacola, unfortunately, the deferBelowFold setting isn't working properly in the current version of Kibana, so we are intending to remove it.

Eventually we will replace this setting with a dashboard option, but there will likely be a few minors with no support for sequential loading.

In the meantime, our best practices recommend making many smaller Dashboards and linking them together with the links panel. I hope this works for you until we can build sequential load or defer below fold functionality into Dashboard.

[bhavyarm]

Raised a bug to remove this as soon as possible from serverless environment - #183166