fix(envd): skip MMDS polling in containerized deployments

[Luckydog691]

What was broken

main.go guards its startup MMDS poll with if !isNotFC, and the -isnotfc flag is documented as "run outside of Firecracker (skips MMDS poll and HTTP log exporter)". The /init handler still started the same 60s polling loop unconditionally: every attempt opens a TCP connection to 169.254.169.254:80, which with no MMDS endpoint reachable stays half-open in SYN_SENT for the whole poll window.

That dangling connection becomes fatal on checkpoint: a gVisor (runsc) checkpoint taken while it exists panics in the TCP endpoint save path (resetConnectionLocked dereferences a nil snd/rcv), so checkpointing fails deterministically for the whole poll window.

Fix

Mirror the guard main.go already applies to its startup poll: skip the MMDS polling in /init when isNotFC is set. Firecracker-based deployments are unchanged.

Verification

• In a containerized deployment, the SYN_SENT connection to 169.254.169.254:80 is observable for ~60s after /init before the change; it never appears after it.
• Checkpointing a runsc sandbox inside that window fails before the change; a checkpoint + restore round trip succeeds after it.
• go build ./... and go test ./internal/api/ pass.

Supersedes #3638. Does not address #3559, which concerns /init retries in Firecracker deployments.

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @Luckydog691 on file. You can sign our CLA at https://e2b.dev/docs/cla . Once you've signed, post a comment here that says '@cla-bot check'

[Luckydog691]

We require contributors to sign our Contributor License Agreement, and we don't have @Luckydog691 on file. You can sign our CLA at https://e2b.dev/docs/cla . Once you've signed, post a comment here that says '@cla-bot check'

@cla-bot check

[cla-bot]

We require contributors to sign our Contributor License Agreement, and we don't have @Luckydog691 on file. You can sign our CLA at https://e2b.dev/docs/cla . Once you've signed, post a comment here that says '@cla-bot check'

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[Luckydog691]

We require contributors to sign our Contributor License Agreement, and we don't have @Luckydog691 on file. You can sign our CLA at https://e2b.dev/docs/cla . Once you've signed, post a comment here that says '@cla-bot check'

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!