Don't plot initial convergence value

This is the value from before running the first iteration. It is not very useful but shifts the plot scale.

mantidimaging/core/reconstruct/cil_recon.py

@@ -45,7 +45,7 @@ def __call__(self, algo: Algorithm) -> None:
         if self.progress:
             extra_info = {}
             if algo.iterations and algo.iterations[-1] == algo.iteration:
-                extra_info = {'iterations': algo.iterations, 'losses': algo.loss}
+                extra_info = {'iterations': algo.iterations[1:], 'losses': algo.loss[1:]}
             if algo.last_residual and algo.last_residual[0] == algo.iteration:
                 extra_info["residual"] = algo.last_residual[1]
             self.progress.update(