zjit_diff: Normalize zjit stats to only the common path suffix

[rwstauner]

Allow stats that have full paths to be compared
by using the common path suffix.

Makes the report a lot less noisy by collapsing into something like this:

OTHER/NEW STATS (showing differences > 5.0%)
--------------------------------------------------------------------------------
  lobsters:
    iseq_calls_count_build_order@.../lib/ruby/gems/4.1.0+1/gems/activerecord-8.1.1/lib/active_record/relation/query_methods.rb:2067                              1 →         14,984 ▲+1498300.0%
    iseq_calls_count_cache_hits@.../lib/ruby/gems/4.1.0+1/gems/actionview-8.1.1/lib/action_view/renderer/renderer.rb:53                                          3 →         14,611 ▲+486933.3%
    iseq_calls_count_data@.../lib/ruby/4.1.0+1/rubygems/stub_specification.rb:105                                                                               53 →          7,178 ▲+13443.4%
    iseq_calls_count_group_values@.../lib/ruby/gems/4.1.0+1/gems/activerecord-8.1.1/lib/active_record/relation/query_methods.rb:175                            621 →         15,604 ▲+2412.7%
    iseq_calls_count_partition_segments@.../lib/ruby/4.1.0+1/rubygems/version.rb:450                                                                            13 →            227 ▲+1646.2%
    iseq_calls_count_normalize_key@.../lib/ruby/gems/4.1.0+1/gems/activesupport-8.1.1/lib/active_support/cache/file_store.rb:163                               677 →          5,051 ▲ +646.1%
    iseq_calls_count_score@.../lib/ruby/gems/4.1.0+1/gems/activemodel-8.1.1/lib/active_model/attribute_methods.rb:273                                        5,542 →         32,060 ▲ +478.5%