idmap2: fix clang-tidy warnings [modernize-*]

Bug: 120024673
Test: mmm frameworks/base/cmds/idmap2; check output
Change-Id: I8768169fb7b541eb6b1aa3311c46a710eb71aac9
diff --git a/cmds/idmap2/tests/FileUtilsTests.cpp b/cmds/idmap2/tests/FileUtilsTests.cpp
index 6584ee3..4bf832a 100644
--- a/cmds/idmap2/tests/FileUtilsTests.cpp
+++ b/cmds/idmap2/tests/FileUtilsTests.cpp
@@ -29,9 +29,7 @@
 
 using ::testing::NotNull;
 
-namespace android {
-namespace idmap2 {
-namespace utils {
+namespace android::idmap2::utils {
 
 TEST(FileUtilsTests, FindFilesFindEverythingNonRecursive) {
   const auto& root = GetTestDataPath();
@@ -71,6 +69,4 @@
   close(pipefd[0]);
 }
 
-}  // namespace utils
-}  // namespace idmap2
-}  // namespace android
+}  // namespace android::idmap2::utils