refactor: update .gitignore and optimize Angular config (!7)

Reviewed-on: https://git.simonis.lol/projects/casino/pulls/7
Reviewed-by: Constantin Simonis <constantin@simonis.lol>
Reviewed-by: Huy <ptran@noreply@simonis.lol>
Co-authored-by: Jan-Marlon Leibl <jleibl@proton.me>
Co-committed-by: Jan-Marlon Leibl <jleibl@proton.me>

frontend/angular.json

@@ -16,9 +16,6 @@
             "outputPath": "dist/lf10-starter2024",
             "index": "src/index.html",
             "browser": "src/main.ts",
-            "polyfills": [
-              "zone.js"
-            ],
             "tsConfig": "tsconfig.app.json",
             "assets": [
               {
@@ -73,10 +70,6 @@
         "test": {
           "builder": "@angular-devkit/build-angular:karma",
           "options": {
-            "polyfills": [
-              "zone.js",
-              "zone.js/testing"
-            ],
             "tsConfig": "tsconfig.spec.json",
             "assets": [
               {