TOKYO, Feb 2 : Japanese Prime Minister Sanae Takaichi faces a crucial markets test in the final run-up to a snap election this weekend where she is hoping a decisive victory will give her a mandate for expansionary fiscal policy. The finance ministry will auction some 700 billion yen ($4.5 billion) of 30-year government bonds on Thursday, three days before polls open.  It's a tenor that has been hyper-sensitive to worries about a loosening of fiscal restraint, suffering a rout last month as