[ruby/rack] Use java_tune.sh script for rack-jruby (#9372)

This should improve `rack-jruby` performance.
Also remove `java_tune.sh` from frameworks that no longer test with
JRuby.

Author: p8

frameworks/Ruby/rack-sequel/config/java_tune.sh renamed to frameworks/Ruby/rack/config/java_tune.sh

@@ -13,4 +13,6 @@ COPY . .
 
 EXPOSE 8080
 
+CMD config/java_tune.sh
+
 CMD bundle exec puma -C config/puma.rb -b tcp://0.0.0.0:8080 -e production