chore(tests): n+1 is sufficient to trigger exception

Signed-off-by: heitorlessa <lessa@amazon.co.uk>

Author: heitorlessa

tests/functional/test_metrics.py

@@ -321,7 +321,7 @@ def test_schema_no_metrics(service, namespace):
 
 def test_exceed_number_of_dimensions(metric, namespace):
     # GIVEN we have more dimensions than CloudWatch supports (N+1)
-    dimensions = [{"name": f"test_{i}", "value": "test"} for i in range(MAX_DIMENSIONS + 2)]
+    dimensions = [{"name": f"test_{i}", "value": "test"} for i in range(MAX_DIMENSIONS + 1)]
 
     # WHEN we attempt to serialize them into a valid EMF object
     # THEN it should fail validation and raise SchemaValidationError