New flag icons (#11553)

* updated flag icons

* remove lines completly

* Visitors in Real-time

* added ti flag

* fix merge

* readd logoHeight

* remove flags from plugins/UserCountry/images/

* change flag directory

* (hopefully) fix all tests

* UserCountry system tests

* Fix tests refs https://github.com/piwik/piwik/pull/11553

* Fixed CustomDimensions tests

* remove unused flags

* remove flag of united nations

* System tests with new path

* light border around flags in goals and live view

* Fix BC system test

* border around flag in visitor profile

* Border around country flags in reports

* border around flag icons in HTML reports

* simpler css

* System tests

* UI tests show new flags + borders around them