Prove the swap-certificates-without-restart promise over real TLS
handshakes (backlog#1154 peri-5): new connections pick up the rotated
certificate within the reload interval, a session opened under the old
certificate survives the swap, and garbage material is fail-safe (the
old certificate keeps serving, the failure leaves a tls_reload_failed
log event, the process stays up). Wired into the e2e-smoke nextest
profile (ci-4 mechanism).
Zhengchao An