Set the LANG when invoking cocoapods (#45710)

diff --git a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
index 44ee1b5..19ae134 100644
--- a/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
+++ b/packages/flutter_tools/test/general.shard/macos/cocoapods_test.dart
@@ -80,12 +80,12 @@
     when(mockProcessManager.run(
       <String>['pod', 'install', '--verbose'],
       workingDirectory: 'project/ios',
-      environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true'},
+      environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true', 'LANG': 'en_US.UTF-8'},
     )).thenAnswer((_) async => exitsHappy());
     when(mockProcessManager.run(
       <String>['pod', 'install', '--verbose'],
       workingDirectory: 'project/macos',
-      environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true'},
+      environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true', 'LANG': 'en_US.UTF-8'},
     )).thenAnswer((_) async => exitsHappy());
   });
 
@@ -368,6 +368,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       )).thenAnswer((_) async => exitsWithError(
         '''
@@ -420,7 +421,7 @@
       verify(mockProcessManager.run(
         <String>['pod', 'install', '--verbose'],
         workingDirectory: 'project/ios',
-        environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true'},
+        environment: <String, String>{'FLUTTER_FRAMEWORK_DIR': 'engine/path', 'COCOAPODS_DISABLE_STATS': 'true', 'LANG': 'en_US.UTF-8'},
       ));
     }, overrides: <Type, Generator>{
       FileSystem: () => fs,
@@ -447,6 +448,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       ));
     }, overrides: <Type, Generator>{
@@ -477,6 +479,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       ));
     }, overrides: <Type, Generator>{
@@ -507,6 +510,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       ));
     }, overrides: <Type, Generator>{
@@ -539,6 +543,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       ));
     }, overrides: <Type, Generator>{
@@ -591,6 +596,7 @@
         environment: <String, String>{
           'FLUTTER_FRAMEWORK_DIR': 'engine/path',
           'COCOAPODS_DISABLE_STATS': 'true',
+          'LANG': 'en_US.UTF-8',
         },
       )).thenAnswer(
         (_) async => exitsWithError()
@@ -621,6 +627,7 @@
         'FLUTTER_FRAMEWORK_DIR': 'engine/path',
         'COCOAPODS_DISABLE_STATS': 'true',
         'CP_REPOS_DIR': cocoapodsRepoDir,
+        'LANG': 'en_US.UTF8',
       };
     });
 
@@ -629,7 +636,6 @@
       fs.file(fs.path.join('project', 'ios', 'Podfile'))
         ..createSync()
         ..writeAsStringSync('Existing Podfile');
-
       when(mockProcessManager.run(
         <String>['pod', 'install', '--verbose'],
         workingDirectory: 'project/ios',