fix(ios): fix pod install --project-directory=ios failing (#37994)

Author: tido64

packages/react-native/scripts/cocoapods/__tests__/codegen_utils-test.rb

@@ -373,7 +373,7 @@ def testUseReactCodegenDiscovery_whenParametersAreGood_executeCodegen
             '[Codegen] warn: using experimental new codegen integration'
         ])
         assert_equal(codegen_utils_mock.get_react_codegen_script_phases_params,  [{
-            :app_path => "~/app",
+            :app_path => app_path,
             :config_file_dir => "",
             :config_key => "codegenConfig",
             :fabric_enabled => false,
@@ -382,7 +382,7 @@ def testUseReactCodegenDiscovery_whenParametersAreGood_executeCodegen
         assert_equal(codegen_utils_mock.get_react_codegen_spec_params,  [{
             :fabric_enabled => false,
             :folly_version=>"2021.07.22.00",
-            :package_json_file => "../node_modules/react-native/package.json",
+            :package_json_file => "#{app_path}/ios/../node_modules/react-native/package.json",
             :script_phases => "echo TestScript"
         }])
         assert_equal(codegen_utils_mock.generate_react_codegen_spec_params,  [{

packages/react-native/scripts/cocoapods/codegen_utils.rb

@@ -313,7 +313,7 @@ def use_react_native_codegen_discovery!(
         :config_key => config_key
       )
       react_codegen_spec = codegen_utils.get_react_codegen_spec(
-        file_manager.join(react_native_path, "package.json"),
+        file_manager.join(relative_installation_root, react_native_path, "package.json"),
         :folly_version => folly_version,
         :fabric_enabled => fabric_enabled,
         :hermes_enabled => hermes_enabled,