[ci] Ubuntu package servers down / degraded

## Description Starting in late April 2026, LightGBM's CI was significantly impacted by unavailability and degraded performance on various services involved in operations like `apt update` and `apt install`. This is mostly out of our control, but opening this issue to track and link things to. ## Reproducible example Sometimes, outright failures like this: ```text Err:7 https://ppa.launchpadcontent.net/git-core/ppa/ubuntu jammy/main amd64 git-man all 1:2.54.0-0ppa1~ubuntu22.04.1 Could not connect to ppa.launchpadcontent.net:443 (185.125.190.80), connection timed out Err:8 https://ppa.launchpadcontent.net/git-core/ppa/ubuntu jammy/main amd64 git amd64 1:2.54.0-0ppa1~ubuntu22.04.1 Unable to connect to ppa.launchpadcontent.net:443: E: Failed to fetch https://ppa.launchpadcontent.net/git-core/ppa/ubuntu/pool/main/g/git/git-man_2.54.0-0ppa1%7eubuntu22.04.1_all.deb Could not connect to ppa.launchpadcontent.net:443 (185.125.190.80), connection timed out Fetched 8073 kB in 37s (216 kB/s) E: Failed to fetch https://ppa.launchpadcontent.net/git-core/ppa/ubuntu/pool/main/g/git/git_2.54.0-0ppa1%7eubuntu22.04.1_amd64.deb Unable to connect to ppa.launchpadcontent.net:443: E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing? Error: Process completed with exit code 100. ``` Then later, after https://status.canonical.com/ seemed to show things as "operational", timeouts like this: ```text Processing triggers for dbus (1.12.20-2ubuntu4.1) ... Traceback (most recent call last): File "/usr/bin/add-apt-repository", line 364, in <module> sys.exit(0 if addaptrepo.main() else 1) File "/usr/bin/add-apt-repository", line 347, in main shortcut = handler(source, **shortcut_params) File "/usr/lib/python3/dist-packages/softwareproperties/shortcuts.py", line 40, in shortcut_handler return handler(shortcut, **kwargs) File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 82, in __init__ if self.lpppa.publish_debug_symbols: File "/usr/lib/python3/dist-packages/softwareproperties/ppa.py", line 120, in lpppa self._lpppa = self.lpteam.getPPAByName(name=self.ppaname) File "/usr/lib/python3/dist-packages/lazr/restfulclient/resource.py", line 592, in __call__ response, content = self.root._browser._request( File "/usr/lib/python3/dist-packages/lazr/restfulclient/_browser.py", line 429, in _request raise error lazr.restfulclient.errors.ServerError: HTTP Error 504: Gateway Time-out ``` ## Environment info N/A ## Additional Comments Some resources: * major incident: https://status.canonical.com/#/incident/KNms6QK9ewuzz-7xUsPsNylV20jEt5kyKsd8A-3ptQEHpOd8VQ40ZQs-KD81fboQXeGZB94okNHdHBGlCv58Sw== * https://www.reddit.com/r/Ubuntu/comments/1t1ov6s/the_major_ubuntu_server_outage_is_over/ * https://www.reddit.com/r/Ubuntu/