libuv 1.49.0 breaks upforwd system test in BIND 9

In BIND 9, the upforwd system test started to fail with libuv 1.49.0:

2024-09-27 15:08:19 INFO:upforwd.test_upforwd     I:checking DNSTAP logging of UPDATE forwarded update replies (28)
2024-09-27 15:08:19 INFO:upforwd.test_upforwd     I:UQ=0 UR=1
2024-09-27 15:08:19 INFO:upforwd.test_upforwd     I:failed

I bisected libuv, and e5cb1d3d3d4ab3178ac567fb6a7f0f4b5eef3083 seems to be the culprit. I believe @bnoordhuis hunch in #4400 came true:

I'm somewhat worried this change may cause hard-to-debug regressions in existing programs

I filed this upstream as https://github.com/libuv/libuv/issues/4584.

For CI consumption, we build libuv 1.48.0 with TSAN enabled for the TSAN image; for non-TSAN image, we pull libuv from Fedora that just got updated to 1.49.1.

@pemensik Given Ben's quote above, you may see weird bugs with the updated libuv in Fedora (in BIND 9 or otherwise).

For now, I'll mark the upforwd system test as xfail to unclog our CI.