⏪️ revert: downgrade JRuby fixture to Rack 2.x for performance

Rack 3.x causes JRuby integration tests to exceed CloudFoundry's 180s
startup timeout. Reverting to Rack 2.x significantly improves startup time:

- Rack: 3.2.4 → 2.2.21
- Sinatra: 4.2.1 → 3.2.0
- rack-protection: 4.2.1 → 3.2.0
- rackup: 2.3.1 → 1.0.1
- Remove: rack-session, logger (not needed with Rack 2)

JRuby has slower JVM startup and warmup with Rack 3's increased overhead.

Author: ramonskie

fixtures/default/sinatra_jruby/Gemfile

@@ -3,5 +3,5 @@ source 'https://rubygems.org'
 ruby '3.1.7', :engine => 'jruby', :engine_version => '9.4.14.0'
 
 gem 'rackup'
-gem 'sinatra'
+gem 'sinatra', '~> 3.0'
 gem 'webrick'

fixtures/default/sinatra_jruby/Gemfile.lock

@@ -2,26 +2,20 @@ GEM
   remote: https://rubygems.org/
   specs:
     base64 (0.3.0)
-    logger (1.7.0)
     mustermann (3.0.4)
       ruby2_keywords (~> 0.0.1)
-    rack (3.2.4)
-    rack-protection (4.2.1)
+    rack (2.2.21)
+    rack-protection (3.2.0)
       base64 (>= 0.1.0)
-      logger (>= 1.6.0)
-      rack (>= 3.0.0, < 4)
-    rack-session (2.1.1)
-      base64 (>= 0.1.0)
-      rack (>= 3.0.0)
-    rackup (2.3.1)
-      rack (>= 3)
+      rack (~> 2.2, >= 2.2.4)
+    rackup (1.0.1)
+      rack (< 3)
+      webrick
     ruby2_keywords (0.0.5)
-    sinatra (4.2.1)
-      logger (>= 1.6.0)
+    sinatra (3.2.0)
       mustermann (~> 3.0)
-      rack (>= 3.0.0, < 4)
-      rack-protection (= 4.2.1)
-      rack-session (>= 2.0.0, < 3)
+      rack (~> 2.2, >= 2.2.4)
+      rack-protection (= 3.2.0)
       tilt (~> 2.0)
     tilt (2.7.0)
     webrick (1.9.2)
@@ -34,7 +28,7 @@ PLATFORMS
 
 DEPENDENCIES
   rackup
-  sinatra
+  sinatra (~> 3.0)
   webrick
 
 RUBY VERSION