fix(ivy): don't throw on unmatched placeholder replacements in i18nPostprocess (#30632)

Depending on which placeholders the translation uses, there are some legitimate cases where we might not use all placeholder replacements in `i18nPostprocess`. For example if some of the placeholders of the original messages have been removed in the translation.

FW-1312 #resolve
PR Close #30632

packages/core/test/acceptance/i18n_spec.ts

@@ -847,8 +847,7 @@ onlyInIvy('Ivy i18n logic').describe('runtime i18n', () => {
           .toEqual('<child><grand-child><div>Bonjour monde!</div></grand-child></child>');
     });
 
-    // FW-1312: Wrong i18n code generated by the compiler when the template has 2 empty `span`
-    xit('should project translations with selectors', () => {
+    it('should project translations with selectors', () => {
       @Component({selector: 'child', template: `<ng-content select="span"></ng-content>`})
       class Child {
       }