Fix the tests for blessed() so they don't break Test::More.

Test::More::is() might need UNIVERSAL::can, which blessed.t deliberately
breaks to test itself.  This moves the call to is() outside the scope
where UNIVERSAL::can is broken.

See https://rt.cpan.org/Ticket/Display.html?id=76171 and
https://rt.cpan.org/Ticket/Display.html?id=76171#txn-1056703