[processor/tailsampling] fix inverted not sampled AND policy

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 open-telemetry#9768
that introduced support for using invert_match within and sub policies.

Author: jamesrwhite

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)
 
 }