chore: refine containers ready condition during image rolling update

[free6om]

/approve

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 37.50000% with 10 lines in your changes missing coverage. Please review.

Project coverage is 64.68%. Comparing base (0da21a0) to head (9de5034). Report is 1 commits behind head on release-0.9.

Files with missing lines	Patch %	Lines
pkg/controller/instanceset/instance_util.go	40.00%	7 Missing and 2 partials :warning:
pkg/controller/instanceset/reconciler_update.go	0.00%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## release-0.9 #8426 +/- ## =============================================== - Coverage 64.81% 64.68% -0.14% =============================================== Files 358 358 Lines 45431 45441 +10 =============================================== - Hits 29447 29394 -53 - Misses 13348 13418 +70 + Partials 2636 2629 -7 ``` | [Flag](https://app.codecov.io/gh/apecloud/kubeblocks/pull/8426/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/apecloud/kubeblocks/pull/8426/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud) | `64.68% <37.50%> (-0.14%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=apecloud#carryforward-flags-in-the-pull-request-comment) to find out more.

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