Disable fuzzy-ruby-server by default in Ruby language servers (#55215)

## Summary

Add `!fuzzy-ruby-server` to the Ruby language servers list in the
default settings so it is opt-in rather than enabled for all users by
default.

This is a prerequisite for merging the Fuzzy Ruby Server support in the
Ruby extension: https://github.com/zed-extensions/ruby/pull/283

As requested by @vitallium in the review comment:
https://github.com/zed-extensions/ruby/pull/283\#issuecomment-4294888519

## Change

```diff
- "language_servers": ["solargraph", "!ruby-lsp", "!rubocop", "!sorbet", "!steep", "!kanayago", "..."],
+ "language_servers": ["solargraph", "!ruby-lsp", "!rubocop", "!sorbet", "!steep", "!kanayago", "!fuzzy-ruby-server", "..."],
```

Release Notes:

- Disabled `fuzzy-ruby-server` by default for Ruby files.

---------

Co-authored-by: Marshall Bowers <git@maxdeviant.com>

assets/settings/default.json

@@ -2255,7 +2255,16 @@
       "language_servers": ["basedpyright", "ruff", "!ty", "!pyrefly", "!pyright", "!pylsp", "..."],
     },
     "Ruby": {
-      "language_servers": ["solargraph", "!ruby-lsp", "!rubocop", "!sorbet", "!steep", "!kanayago", "..."],
+      "language_servers": [
+        "solargraph",
+        "!ruby-lsp",
+        "!rubocop",
+        "!sorbet",
+        "!steep",
+        "!kanayago",
+        "!fuzzy-ruby-server",
+        "...",
+      ],
     },
     "Rust": {
       "debuggers": ["CodeLLDB"],