As a reminder, PRs marked as draft will not be automatically assigned reviewers,
or be handled by maintainer-oncall triage.

Please mark your PR as ready when you want it to be reviewed!

macos test failure appears unrelated:

ERROR: /private/var/tmp/_bazel_runner/3d1a7f52fd47fc9a8db71770aacd13e5/external/bazel_tools/tools/cpp/BUILD:469:14: Target '@bazel_tools//tools/cpp:compiler' depends on toolchain '@local_config_cc//:cc-compiler-darwin', which cannot be found: error loading package '@local_config_cc//':***@local_config_cc_toolchains//:osx_archs.bzl': no such file'

Sorry why is this change needed?

These factories were registered with the suffix "Impl" but declared without the suffix:

• REGISTER_FACTORY(AppleDnsResolverFactoryImpl, DnsResolverFactory); / DECLARE_FACTORY(AppleDnsResolverFactory);
• REGISTER_FACTORY(CaresDnsResolverFactoryImpl, DnsResolverFactory); / DECLARE_FACTORY(CaresDnsResolverFactory);

This was my mistake when adding the declarations in #18646, since I went based off of the convention of other factories being declared without the "Impl" suffix and didn't notice that the registration was using a different name.

This manifested as a linker error when attempting to link anything using the extension because that symbol wasn't being emitted in the binary:

Undefined symbols for architecture x86_64:
  "Envoy::Network::forceRegisterAppleDnsResolverFactory()", referenced from:
      Envoy::ExtensionRegistryPlatformAdditions::registerFactories() in libextension_registry_platform_additions.lo(extension_registry_apple.o)
ld: symbol(s) not found for architecture x86_64

Ah OK got it, thanks. LGTM.