fix: display the right bottom slope value when a parametric section is generated

Refs #654

src/app/services/formulaire.service.ts

+/* eslint-disable @typescript-eslint/member-ordering */
 
 import { Injectable } from "@angular/core";
 import { decode } from "he";
@@ -872,8 +873,12 @@ export class FormulaireService extends Observable {
         if (this.currentForm.currentNub instanceof SectionNub) {
             const sn: SectionNub = this.currentForm.currentNub;
             if (sn instanceof RegimeUniforme || sn instanceof CourbeRemous) {
+                // change _If visibility to copy section
+                sn.section.prms.If.visible = true;
                 // copy section
                 const serialisedSection = sn.section.serialise();
+                // Reinitialize _If visibility
+                sn.section.prms.If.visible = false;
                 const sectionCopy: acSection = Session.getInstance().unserialiseSingleNub(serialisedSection, false).nub as acSection;
                 if (Y !== undefined) {
                     sectionCopy.prms.Y.singleValue = Y;