perf_hooks: fix timerify() inconsistency for rejected thenables

[batuhan-bas]

Summary

timerify() behaves inconsistently depending on whether the wrapped
function throws synchronously or returns a rejected thenable:

function f1() { throw new Error() }
async function f2() { throw new Error() }

const h1 = perf_hooks.createHistogram();
const h2 = perf_hooks.createHistogram();
const g1 = perf_hooks.performance.timerify(f1, { histogram: h1 });
const g2 = perf_hooks.performance.timerify(f2, { histogram: h2 });

try { g1(); } catch {}
await g2().catch(() => {});

h1.count === h2.count // expected true, actual false

g1() throws before the code ever reaches the recording step, so
nothing is recorded. g2() returns a rejected promise, and
timerify() records via Promise.prototype.finally(), which runs on
both fulfillment and rejection — so the async throw is recorded.

Fix

Use .then() with only an onFulfilled handler instead of
.finally(). This records only on fulfillment, matching the
synchronous case, while the rejection still propagates through the
returned promise unchanged. It also avoids assuming the returned
thenable implements finally(), which isn't part of the minimal
thenable contract (only then() is required).

Test plan

• Added test/parallel/test-perf-hooks-timerify-async-error.js,
  asserting a rejected thenable produces no histogram record and no
  'function' performance entry.
• Ran the full existing test-perf-hooks-timerify-* suite locally,
  all passing.

Fixes: #42743