tests: re-enable 2086, and 472, 1299, 1613 for Windows

- GHA/windows: un-ignore tests 472 1299 1613.
  They were ignored for the mingw-w64 c-ares U job.
  They do run fine now:
  https://github.com/curl/curl/actions/runs/12032875421/job/33547724780?pr=15644

- globally re-enable test 2086.
  Comment says it only affected Windows.
  Seems to be running fine now. Example:
  Windows:
  https://github.com/curl/curl/actions/runs/12032875421/job/33547718309?pr=15644#step:13:3856
  Linux:
  https://github.com/curl/curl/actions/runs/12032875397/job/33545739712#step:41:3650

- update comments for disabled tests 1184, 1801.
  They affect all operating systems, likely all CIs.

  FAIL 1801: 'HTTP/2 upgrade with lying server' HTTP, HTTP/2
  https://github.com/curl/curl/actions/runs/12032362497/job/33544053001#step:14:4265
  FAIL 1184: 'HTTP 1.1 CONNECT with redirect and set -H user-agent' HTTP, HTTP CONNECT, HTTP proxy, proxytunnel
  https://github.com/curl/curl/actions/runs/12032362497/job/33544051415#step:14:5252

Closes #15644

tests/data/DISABLED

@@ -39,7 +39,7 @@
 # of running runtests.pl as a child of itself sharing
 # some of the directories.
 1182
-# test 1184 causes flakiness in CI builds, mostly visible on macOS
+# test 1184 causes flakiness in CI builds
 1184
 1209
 1211
@@ -50,11 +50,9 @@
 # example: https://travis-ci.org/curl/curl/builds/81633600
 1510
 1512
-# test 1801 causes problems on macOS and GitHub
+# test 1801 causes problems in CI builds
 # https://github.com/curl/curl/issues/380
 1801
-# test 2086 causes issues on Windows only
-2086
 #
 #
 # Tests that are disabled here for Hyper are SUPPOSED to work but