Rewrite to use less iterations

[StFroese]

TITRATE/titrate/upperlimits.py

Lines 57 to 62 in fee2576

	while self.pvalue(poi_ul, cl_type=self.cl_type) > 1 - self.cl or np.isnan(
	self.pvalue(poi_ul, cl_type=self.cl_type)
	):
	poi_ul *= 2
	interp_ul_points = np.linspace(poi_ul / 2, poi_ul, 10)

Rewrite this to store pvalue during loop and store last values