[ZSvirt] doc: sdk: comment says 505 but code checks 503

[chayu163]

Description

In org.zstack.sdk.ZSClient.asyncPollResult, the comment above the response
handling reads:

// 200 means the task has been completed successfully,
// or a 505 indicates a failure,
// otherwise a 202 returned means it is still
// in processing
if (response.code() == 200 || response.code() == 503) {

The code actually checks for status code 503 (as does the code a few lines
above in the guard, response.code() != 200 && response.code() != 503 && response.code() != 202),
but the comment mentions 505. The comment and the implementation disagree.

Expected behavior

The comment should match the implemented status code.

Proposed fix

// or a 503 indicates a failure,