[analysis_server] Revert to short-mode formatting for pkg:language_server_protocol

This code generation was previously formatting generated files using the latest version. In 76feb10829 I re-ran the formatter to get the new formatting style.

However recently, a pre-submit hook to verify formatting was enabled and revealed that pkg:language_server_protocol still has an older SDK constraint, so the presubmit fails (if you modify these files).

There are two options:

1. Restore formatting to the previous version for pkg:language_server_protocol
2. Increase the SDK constraint for pkg:language_server_protocol

I picked the first for now, since analyzer_server_plugin also depends on pkg:language_server_protocol and currently has a constraint of 3.3, and I don't want to mess with that just to fix the format presubmit.

Change-Id: I2347577561e659825b444ef6622d646c6e513aea
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/401001
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Samuel Rawlins <srawlins@google.com>

pkg/analysis_server/tool/lsp_spec/codegen_dart.dart

@@ -17,7 +17,9 @@ import 'generate_all.dart';
 import 'meta_model.dart';
 
 final formatter = DartFormatter(
-  languageVersion: DartFormatter.latestLanguageVersion,
+  // The language_server_protocol package is currently still using a lower
+  // SDK constraint so pre-commit hooks require it matches short style.
+  languageVersion: DartFormatter.latestShortStyleLanguageVersion,
 );
 
 final _canParseFunctions = SplayTreeMap<String, String>();