ci: Disable FreeBSD builds (#34511)

Recently FreeBSD zed-remote-server builds are failing 90%+ of the time
for unknown reasons.

Temporarily suspend them.

Example failing builds:
- [2025-07-15 16:15 Nightly
Failure](https://github.com/zed-industries/zed/actions/runs/16302777887/job/46042358675)
- [2025-07-15 12:20 Nightly
Success](https://github.com/zed-industries/zed/actions/runs/16297907892/job/46025281518)
- [2025-07-14 08:21 Nightly
Failure](https://github.com/zed-industries/zed/actions/runs/16266193889/job/45923004940)
- [2025-06-17 Nightly
Failure](https://github.com/zed-industries/zed/actions/runs/15700462603/job/44234573761)

Release Notes:

- Temporarily disable FreeBSD zed-remote-server builds due to CI failures.

.github/workflows/release_nightly.yml

@@ -187,7 +187,7 @@ jobs:
 
   freebsd:
     timeout-minutes: 60
-    if: github.repository_owner == 'zed-industries'
+    if: false && github.repository_owner == 'zed-industries'
     runs-on: github-8vcpu-ubuntu-2404
     needs: tests
     name: Build Zed on FreeBSD