Per spider DNS_RESOLVER doesn't work

[synodriver]

Description

The spider with following settings

class ExampleSpider(scrapy.Spider):
    name = "example"
    allowed_domains = ["example.com"]
    start_urls = ["https://example.com"]
    custom_settings = {
         "DNS_RESOLVER": "test1.resolver.CachingAsyncDohResolver"
     }

do not follow the custom_settings

Steps to Reproduce

1. Use the following code (merely an example)

   
   import asyncio
   import json
   import re
   import socket
   from typing import List, Optional

import aiodns import aiohttp import scrapy.crawler from scrapy.resolver import CachingThreadedResolver, dnscache from scrapy.utils.defer import deferred_from_coro from twisted.internet.interfaces import IResolverSimple from zope.interface.declarations import implementer

@implementer(IResolverSimple) class CachingAsyncResolver(CachingThreadedResolver): """ Async caching resolver. Require aiodns """

def __init__(
    self,
    reactor,
    cache_size,
    timeout,
    nameservers: Optional[List[str]] = None,
    **kwargs,
):
    super().__init__(reactor, cache_size, timeout)
    self._resolver = aiodns.DNSResolver(nameservers, None, **kwargs)
    self._pattern = re.compile(
        r"((\d|[1-9]\d|1\d\d|2[0-4]\d|25[0-5])\.){3}(1\d\d|2[0-4]\d|25[0-5]|[1-9]\d|\d)"
    )

@classmethod
def from_crawler(cls, crawler: scrapy.crawler.Crawler, reactor):
    if crawler.settings.getbool("DNSCACHE_ENABLED"):
        cache_size = crawler.settings.getint("DNSCACHE_SIZE")
    else:
        cache_size = 0
    return cls(
        reactor,
        cache_size,
        crawler.settings.getfloat("DNS_TIMEOUT"),
        crawler.settings.getlist("AIODNS_NAMESERVERS", None),
        **crawler.settings.getdict("AIODNS_KW", {}),
    )

def getHostByName(self, name, timeout=None):
    print(f"resolving name {name}")
    return deferred_from_coro(self._getHostByName(name, timeout))

async def _getHostByName(self, name, timeout=None):
    if self._pattern.match(name) is not None:  # just an ip
        return name
    if name in dnscache:
        return dnscache[name]
    try:
        resp = await asyncio.wait_for(
            self._resolver.gethostbyname(name, socket.AF_INET), timeout
        )
        result = resp.addresses[0]
        self._cache_result(result, name)
        return result
    except asyncio.TimeoutError:
        raise
    except aiodns.error.DNSError as exc:
        msg = exc.args[1] if len(exc.args) >= 1 else "DNS lookup failed"
        raise OSError(msg) from exc

And run spider

**Expected behavior:** The log by that resolver is seen

**Actual behavior:** The crawler didn't call that resolver

**Reproduces how often:** Always, both on linux and windows

### Versions

Scrapy       : 2.11.1
lxml         : 4.9.2.0
libxml2      : 2.9.12
cssselect    : 1.2.0
parsel       : 1.8.1
w3lib        : 2.1.1
Twisted      : 24.3.0
Python       : 3.10.12 | packaged by conda-forge | (main, Jun 23 2023, 22:34:57) [MSC v.1936 64 bit (AMD64)]
pyOpenSSL    : 23.3.0 (OpenSSL 3.1.4 24 Oct 2023)
cryptography : 41.0.5
Platform     : Windows-10-10.0.19045-SP0

Scrapy       : 2.11.1
lxml         : 4.9.2.0
libxml2      : 2.9.14
cssselect    : 1.2.0
parsel       : 1.8.1
w3lib        : 2.1.1
Twisted      : 24.3.0
Python       : 3.10.11 (main, Apr 20 2023, 19:02:41) [GCC 11.2.0]
pyOpenSSL    : 23.1.1 (OpenSSL 3.1.0 14 Mar 2023)
cryptography : 40.0.2
Platform     : Linux-5.10.0-13-amd64-x86_64-with-glibc2.31

### Additional context

It works if you put it into global settings.py

[wRAR]

Duplicate of #5988