[processor/tailsampling] fix InvertNotSampled decision precedence w…

…hen inside and sub policy (#33671)

**Description:**

This fixes the handling of AND policies that contain a sub-policy with
invert_match=true. Previously if the decision from a policy evaluation
was `NotSampled` or `InvertNotSampled` it would return a `NotSampled`
decision regardless, effectively downgrading the result.

This was breaking the documented behaviour that inverted decisions
should take precedence over all others.

This is related to the changes made in
#9768 that introduced
support for using invert_match within and sub policies.

**Link to tracking Issue:**
#33656

**Testing:**

I tested manually that this fixes the issue described in
#33656
and also updated the tests. If you have any suggestions for more tests
we could add let me know.

**Documentation:**

.chloggen/fix-tailsampling-and-policy-precedence.yaml

@@ -0,0 +1,9 @@
+change_type: bug_fix
+component: tailsamplingprocessor
+note: Fix precedence of inverted match in and policy
+issues: [33671]
+subtext: |
+ Previously if the decision from a policy evaluation was `NotSampled` or `InvertNotSampled` it would return a `NotSampled` decision regardless, effectively downgrading the result.
+
+ This was breaking the documented behaviour that inverted decisions should take precedence over all others.
+change_logs: [user]

processor/tailsamplingprocessor/internal/sampling/and.go

@@ -30,14 +30,14 @@ func NewAnd(
 // Evaluate looks at the trace data and returns a corresponding SamplingDecision.
 func (c *And) Evaluate(ctx context.Context, traceID pcommon.TraceID, trace *TraceData) (Decision, error) {
  // The policy iterates over all sub-policies and returns Sampled if all sub-policies returned a Sampled Decision.
- // If any subpolicy returns NotSampled, it returns NotSampled Decision.
+ // If any subpolicy returns NotSampled or InvertNotSampled it returns that
  for _, sub := range c.subpolicies {
  decision, err := sub.Evaluate(ctx, traceID, trace)
  if err != nil {
  return Unspecified, err
  }
  if decision == NotSampled || decision == InvertNotSampled {
- return NotSampled, nil
+ return decision, nil
  }
 
  }

processor/tailsamplingprocessor/internal/sampling/and_test.go

@@ -113,6 +113,6 @@ func TestAndEvaluatorStringInvertNotSampled(t *testing.T) {
  }
  decision, err := and.Evaluate(context.Background(), traceID, trace)
  require.NoError(t, err, "Failed to evaluate and policy: %v", err)
- assert.Equal(t, decision, NotSampled)
+ assert.Equal(t, decision, InvertNotSampled)
 
 }