Qt metrics v1.5.4: Minor CI metrics refactoring

The number of Ajax calls sent when pressing the "Clear filters" button
optimized to one by changing the CI metrics page module to use one
function call instead of several. This is pure implementation change
and is not visible to the user.

Change-Id: I346fd4db88553b45c4b54ba33485dccb31ca8636
Reviewed-by: Tony Sarajärvi <tony.sarajarvi@digia.com>