Revert "[devicelab] measure entire release folder size, zipped (#115612)" (#115617)

This reverts commit 0b33b859.

dev/devicelab/lib/tasks/perf_tests.dart

@@ -1513,29 +1513,19 @@ class CompileTest {
         watch.start();
         await flutter('build', options: options);
         watch.stop();
-        final String buildPath = path.join(
+        final String basename = path.basename(cwd);
+        final String exePath = path.join(
           cwd,
           'build',
           'windows',
           'runner',
           'release',
-        );
+          '$basename.exe');
+        final File exe = file(exePath);
         // On Windows, we do not produce a single installation package file,
-        // rather a directory containing an .exe and .dll files. Zip them all
-        // together to get an approximate release size.
-        final int result = await exec('tar.exe', <String>['-zcf', 'build/app.tar.gz', '"$buildPath"']);
-        if (result == 0) {
-          final File outputFile = file('build/app.tar.gz');
-          if (outputFile.existsSync()) {
-            releaseSizeInBytes = outputFile.lengthSync();
-          } else {
-            print('tar completed successfully, but ${outputFile.path} does not exist!');
-            releaseSizeInBytes = 0;
-          }
-        } else {
-          print('Failed to run tar.exe: $result');
-          releaseSizeInBytes = 0;
-        }
+        // rather a directory containing an .exe and .dll files.
+        // The release size is set to the size of the produced .exe file
+        releaseSizeInBytes = exe.lengthSync();
         break;
     }