Improve incremental outerloops performance

[jeandemanged]

Describe the current behavior

Sensitivity calculation can be slow when using incremental outerloops on large networks

Describe the expected behavior

Smaller computation time

Describe the motivation

A first optimization was done at OLF level in #895, consisting in avoiding unnecessary sensitivity calculations.

But as mentioned in https://github.com/powsybl/powsybl-open-loadflow/pull/895#issuecomment-1807143945, we can do much better.

Extra Information

No response