Use 1.1.1.1 instead of 8.8.8.8 as IP for network check.

[concretevitamin]

We've seen reports that 8.8.8.8 can be unreachable (#1767).

Changes to Cloudflare's 1.1.1.1 as a mitigation.

Tested (run the relevant ones):

• Any manual or new tests for this PR (please specify below)
• (US) sky launch --cloud gcp --down
• Confirmed with friend in China that 1.1.1.1 is reachable

[romilbhardwaj]

Thanks for the fix!

BTW perhaps we should add redundancy in our network checks ("try 8.8.8.8 or 1.1.1.1, if either works == all good"). Feel free to file an issue for that to fix later.

[concretevitamin]

BTW perhaps we should add redundancy in our network checks ("try 8.8.8.8 or 1.1.1.1, if either works == all good"). Feel free to file an issue for that to fix later.

Yeah. Also, thinking we should get rid of this network check in the future if possible (to guard against whatever IP we use being blocked somewhere, or the IP changes, etc.).