DEBUG-2334 run all existing DI tests only on supported configurations

Dynamic instrumentation will not work on Ruby 2.5 and JRuby.
Some unit tests will pass on those configurations, but there is
no reason to run them there because they run on all of the
supported configurations already.

spec/datadog/di/probe_builder_spec.rb

@@ -1,6 +1,8 @@
 require "datadog/di/probe_builder"
 
 RSpec.describe Datadog::DI::ProbeBuilder do
+  di_test
+
   describe ".build_from_remote_config" do
     let(:probe) do
       described_class.build_from_remote_config(rc_probe_spec)

spec/datadog/di/probe_spec.rb

@@ -1,6 +1,8 @@
 require "datadog/di/probe"
 
 RSpec.describe Datadog::DI::Probe do
+  di_test
+
   shared_context "method probe" do
     let(:probe) do
       described_class.new(id: "42", type: "foo", type_name: "Foo", method_name: "bar")