bench: explicitly make all current benchmarks "high" priority

no-functional changes. Only have set the priority level explicitly
on every BENCHMARK macro call.

src/bench/verify_script.cpp

@@ -96,5 +96,5 @@ static void VerifyNestedIfScript(benchmark::Bench& bench)
     });
 }
 
-BENCHMARK(VerifyScriptBench);
-BENCHMARK(VerifyNestedIfScript);
+BENCHMARK(VerifyScriptBench, benchmark::PriorityLevel::HIGH);
+BENCHMARK(VerifyNestedIfScript, benchmark::PriorityLevel::HIGH);