Do not use "Default" as custom profile, global profile
uses "Default" as storge name, this ends up
on creating two browser context adapters using the same files.

Change-Id: I298fa87ee14c5c83a15683710ba3fbb29c201714
Reviewed-by: Peter Varga <pvarga@inf.u-szeged.hu>
Reviewed-by: Alexandru Croitor <alexandru.croitor@qt.io>