Skips jsonifier benchmarks (#6217)

build-constraints.yaml

@@ -7555,6 +7555,8 @@ expected-benchmark-failures:
 # or if Setup fails because of missing foreign libraries.
 # Otherwise place them in expected-benchmark-failures.
 skipped-benchmarks:
+    # aeson-2
+    - jsonifier
 
     # Cyclic dependencies
     - attoparsec