Add form existence check to GeneralTabComponent template

- Added *ngIf="assignedSiteForm" to wrapper div to prevent rendering before form is initialized
- This ensures the component only renders after ngOnInit() has created the form
- Fixes issue where tabs were not visible in Cypress e2e tests
- The form is created in ngOnInit() but template binding happens immediately on component creation

Co-authored-by: renemadsen <[email protected]>

Author: Copilot

eform-client/src/app/plugins/modules/time-planning-pn/components/plannings/time-planning-actions/assigned-site/tabs/general-tab.component.html

@@ -1,4 +1,4 @@
-<div [formGroup]="assignedSiteForm">
+<div [formGroup]="assignedSiteForm" *ngIf="assignedSiteForm">
 <div class="d-flex flex-row" *ngIf="!data.resigned && isFirstUser">
   <!-- data.useGoogleSheetAsDefault -->
   <mat-checkbox class="p-1"