tests: Disable flaky tests on windowns again (#2267)

## Description

This reverts commit 93bcaa5.

Re-opens #2086

## Breaking Changes

<!-- Optional, if there are any breaking changes document them,
including how to migrate older code. -->

## Notes & open questions

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## Change checklist

- [x] Self-review.
- [x] Documentation updates if relevant.
- [x] Tests if relevant.
- [x] All breaking changes documented.

iroh-net/src/dns.rs

@@ -155,6 +155,7 @@ pub(crate) mod tests {
     use super::*;
 
     #[tokio::test]
+    #[cfg_attr(target_os = "windows", ignore = "flaky")]
     async fn test_dns_lookup_basic() {
         let _logging = iroh_test::logging::setup();
         let resolver = default_resolver();
@@ -165,6 +166,7 @@ pub(crate) mod tests {
     }
 
     #[tokio::test]
+    #[cfg_attr(target_os = "windows", ignore = "flaky")]
     async fn test_dns_lookup_ipv4_ipv6() {
         let _logging = iroh_test::logging::setup();
         let resolver = default_resolver();