Fix release-helper Windows issues (#6684)

- Fix a Windows issue caused by trying to run `devtools_tool` without `.bat`
- ~~Fix handling of arguments to git for commit message (https://github.com/flutter/devtools/issues/6679)~~

Edit: Removed the non-Windows parts because they're being handled in https://github.com/flutter/devtools/pull/6685

tool/lib/commands/release_helper.dart

diff --git a/tool/lib/commands/release_helper.dart b/tool/lib/commands/release_helper.dart
index e59247c..61a750c 100644
--- a/tool/lib/commands/release_helper.dart
+++ b/tool/lib/commands/release_helper.dart
@@ -79,20 +79,11 @@
       );
 
       print("Setting the release version.");
-      await processManager.runProcess(
-        CliCommand.from('devtools_tool', [
-          'update-version',
-          'auto',
-          '--type',
-          'release',
-        ]),
-      );
+      await processManager
+          .runProcess(CliCommand.tool('update-version auto --type release'));
 
       final getNewVersionResult = await processManager.runProcess(
-        CliCommand.from('devtools_tool', [
-          'update-version',
-          'current-version',
-        ]),
+        CliCommand.tool('update-version current-version'),
       );
 
       final newVersion = getNewVersionResult;