Update buildpack to use Ruby 3.4.7, addressing YAML loading changes in Psych 4.0+, adding required standard library gems, and modernizing Ruby syntax. All core utility specs (266 examples) pass successfully.

Key changes:
- Update YAML.load_file calls to use permitted_classes and aliases parameters
- Add Psych::DisallowedClass to exception handling
- Include base64, bigdecimal, digest, set, and tmpdir gems explicitly
- Adopt endless range syntax (tokens[1..] vs tokens[1..-1])
- Remove Ruby 2.x version-specific test code
- Modernize RuboCop configuration for rubocop-rspec

Add racc gem required by RuboCop parser in Ruby 3.4+, and update RuboCop
to version 1.60+ which recognizes Ruby 3.4 as a supported version.

Key changes:
- Add racc gem (required by parser gem in Ruby 3.4+)
- Update rubocop from 1.28.2 to 1.81.7 (adds Ruby 3.4 support)
- Update rubocop-rspec from 2.10.0 to 3.8.0
- Modernize .rubocop.yml configuration:
  - Change 'require' to 'plugins' (new preferred syntax)
  - Replace deprecated RSpec/FilePath with RSpec/SpecFilePathFormat and
    RSpec/SpecFilePathSuffix
  - Update RSpec/VerifiedDoubleReference config (obsolete EnforcedStyle)

This allows the buildpack's code quality tools to work with Ruby 3.4.7.

Add missing sub_configuration_context helper method to
java_memory_assistant_spec.rb. This test has been broken since it was
originally added in commit f2eee85 (Oct 26, 2016).

The test references sub_configuration_context() on line 59 but never
defined the helper method. Other specs (tomcat_spec.rb,
open_jdk_like_spec.rb, ibm_jre_spec.rb) each define their own local
helper following the same pattern.

This is a pre-existing bug unrelated to the Ruby 3.4 migration - the
test would have failed on any Ruby version (2.5, 2.6, 2.7, 3.0, 3.1, 3.4)
with NoMethodError for undefined method 'sub_configuration_context'.

Fixes #436 (original PR where test was introduced)

- Update TomcatGeodeStore to properly create XML documents with REXML
- Ruby 3.4's REXML no longer allows creating documents with just XML declaration
- Remove trailing whitespace from XML fixture files (REXML Pretty formatter now strips these)
- All 972 non-integration tests now passing

- Remove bionic (Ubuntu 18.04 EOL April 2023) from PLATFORMS
- Add noble (Ubuntu 24.04 LTS) to PLATFORMS for future support
- Keep jammy (Ubuntu 22.04 LTS) as primary supported platform
- Update all documentation references from bionic to jammy
- Aligns buildpack with Ubuntu LTS lifecycle and support dates

The platform detection at runtime already supported all Ubuntu codenames
via /etc/os-release parsing. This change only affects offline buildpack
packaging (which platforms to cache) and documentation examples.

- Update base image from ubuntu:bionic to ubuntu:jammy
- Remove old Ruby versions (2.5.9, 2.7.6, 3.0.4, 3.1.3)
- Install only Ruby 3.4.7 and set as global default
- Update libssl1.0-dev to libssl-dev for jammy compatibility
- Update python to python3 (Python 2 removed from jammy)
- Align bundler version with Gemfile.lock (2.3.12)

This streamlines CI builds and aligns with the Ruby 3.4.7 migration.
Reduces Docker image build time and size by removing 3 unused Ruby
versions.

Migration to ruby 3.4.7

… of system Ruby

…lity

Fix Ruby version compatibility by always using buildpack Ruby

Bump JProfiler version with regard to security vulnerabilities