UID2-7162 Azure CC: Wait until SKR is running before starting Operator

[swibi-ttd]

Summary
Wait for the SKR sidecar to accept TCP connections on localhost:9000 before launching the JVM in Azure CC operator startup. Intended to close a startup race that caused BAD_PAYLOAD attestation failures.

Background

• While testing the SKR 2.3 → 2.14 upgrade, uid2-core integ logged BAD_PAYLOAD / "Cannot verify payload with the signature" attestation failures on operator start, immediately followed by successful attestation a few seconds later.
• Likely cause: Operator was starting before the SKR sidecar's was running

Changes

• _validate_auxiliaries: rewrite to TCP-probe localhost:9000 with the same retry/backoff structure as before. 15 attempts, exponential delay, fatal on timeout.
• run_compute: call _validate_auxiliaries() between _setup_auxiliaries() and __run_operator(). Matches the AWS pattern.
• _setup_auxiliaries: add a comment explaining why it's intentionally a no-op for Azure CC (SKR is started by ACI, not by us).
• Add SKR_HOST / SKR_PORT as class-level constants on AZR.

Verification

Deployed to Azure integ as snapshot 5.70.111-alpha-259-SNAPSHOT. Startup log shows the new path executing cleanly:

  INFO:root:Start Azure
  ...
  INFO:root:Waiting for SKR sidecar on localhost:9000 ...
  INFO:root:SKR sidecar is ready.
  ...
  09:42:27.669 ... Startup in 11576 ms