test: rely less on duplicative common test harness utilities

There are several cleanups here that are not just style nits...

1. The `common.isMainThread` was just a passthrough to the
   `isMainThread` export on the worker_thread module. It's
   use was inconsistent and just obfuscated the fact that
   the test file depend on the `worker_threads` built-in.
   By eliminating it we simplify the test harness a bit and
   make it clearer which tests depend on the worker_threads
   check.
2. The `common.isDumbTerminal` is fairly unnecesary since
   that just wraps a public API check.
3. Several of the `common.skipIf....` checks were inconsistently
   used and really don't need to be separate utility functions.

A key part of the motivation here is to work towards making more
of the tests more self-contained and less reliant on the common
test harness where possible.

PR-URL: https://github.com/nodejs/node/pull/56712
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

test/internet/test-trace-events-dns.js

@@ -5,9 +5,11 @@ const cp = require('child_process');
 const tmpdir = require('../common/tmpdir');
 const fs = require('fs');
 const util = require('util');
+const { isMainThread } = require('worker_threads');
 
-if (!common.isMainThread)
+if (!isMainThread) {
   common.skip('process.chdir is not available in Workers');
+}
 
 const traceFile = 'node_trace.1.log';