[PROF-10422] Fix flaky GVL profiling integration spec

spec/datadog/profiling/collectors/cpu_and_wall_time_worker_spec.rb

@@ -449,16 +449,25 @@
           samples = samples_for_thread(
             samples_from_pprof_without_gc_and_overhead(recorder.serialize!),
             background_thread_affected_by_gvl_contention
-          )
+          ).sort_by { |s| s.labels.fetch(:end_timestamp_ns) }
+
+          # Because the background_thread_affected_by_gvl_contention starts BEFORE the profiler, the first few samples
+          # will have an unknown state because the profiler may have missed the beginning of the Waiting for GVL
+          #
+          # So that the below assertions make sense (and are not flaky), we drop these first few samples from our
+          # consideration
+          missed_by_profiler_time =
+            samples.take_while { |s| s.labels[:state] == "unknown" }.sum { |sample| sample.values.fetch(:"wall-time") }
 
           waiting_for_gvl_samples = samples.select { |sample| sample.labels[:state] == "waiting for gvl" }
-          total_time = samples.sum { |sample| sample.values.fetch(:"wall-time") }
+          total_time = samples.sum { |sample| sample.values.fetch(:"wall-time") } - missed_by_profiler_time
           waiting_for_gvl_time = waiting_for_gvl_samples.sum { |sample| sample.values.fetch(:"wall-time") }
 
           expect(waiting_for_gvl_samples.size).to be > 0
 
           # The background thread should spend almost all of its time waiting to run (since when it gets to run
           # it just passes and starts waiting)
+          expect(total_time).to be >= 200_000_000 # This test should run for at least 200ms, which is how long we sleep for
           expect(waiting_for_gvl_time).to be < total_time
           expect(waiting_for_gvl_time).to be_within(5).percent_of(total_time)