fix: removed unnecessary checks (flutter#93735)

Author: vlkonoshenko

packages/flutter_tools/lib/src/android/android_sdk.dart

@@ -198,7 +198,7 @@ class AndroidSdk {
       }
     }
 
-    for (final String searchPath in searchPaths.whereType<String>()) {
+    for (final String searchPath in searchPaths) {
       if (globals.fs.directory(searchPath).existsSync()) {
         return searchPath;
       }

packages/flutter_tools/test/general.shard/update_packages_test.dart

@@ -108,7 +108,7 @@ void main() {
     // Create already parsed pubspecs.
     final PubspecYaml flutterPubspec = PubspecYaml(flutter);
 
-    final PubspecDependency gitDependency = flutterPubspec.dependencies.whereType<PubspecDependency>().firstWhere((PubspecDependency dep) => dep.kind == DependencyKind.git);
+    final PubspecDependency gitDependency = flutterPubspec.dependencies.firstWhere((PubspecDependency dep) => dep.kind == DependencyKind.git);
     expect(
       gitDependency.lockLine,
       '''