test(std): make test output less noisy (#8445)

This commit makes output of std/ tests less noisy
by passing "--quiet" flag to Deno subprocesses run
as part of test suite.

std/examples/curl_test.ts

@@ -20,6 +20,7 @@ Deno.test({
       cmd: [
         Deno.execPath(),
         "run",
+        "--quiet",
         "--allow-net",
         "curl.ts",
         "http://localhost:8081",