Updating FlinkDeployment interpreter to display error status, improving health interpreter

[mszacillo]

What type of PR is this?
/kind feature

What this PR does / why we need it:
After doing some load testing of the FlinkDeployment failover (which overall has been looking quite good, but may need to address a couple edge cases), I found that the interpreter is missing one of the ephemeral states that FlinkDeployments can transition through.

Occasionally on failover, the FlinkDeployment will transition from RECONCILING -> INITIALIZING -> CREATED, before finally ending on RUNNING. Additionally, we can make use of the status.error field to further improve the health interpretation.

In this PR I've added:

1. INITIALIZING state as an ephemeral state which we should check during health interpretation.
2. Checking if status.error != nil. If the deployment has a published error, then we treat it as healthy, as this indicates that the job failed due to user error. In the future, we may consider adding an ignore list of errors which we would like to failover.

Which issue(s) this PR fixes:
Fixes #6023

Does this PR introduce a user-facing change?:

`karmada-controller-manager`: FlinkDeployment health interpreter improvements, adding status.error to reflected status

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Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 48.11%. Comparing base (820fd06) to head (f14e0f9).
Report is 18 commits behind head on master.

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Additional details and impacted files

@@            Coverage Diff             @@
##           master    #6073      +/-   ##
==========================================
- Coverage   48.33%   48.11%   -0.23%     
==========================================
  Files         666      668       +2     
  Lines       54858    55163     +305     
==========================================
+ Hits        26518    26541      +23     
- Misses      26616    26896     +280     
- Partials     1724     1726       +2     

Flag	Coverage Δ
unittests	48.11% <ø> (-0.23%)	⬇️

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[RainbowMango]

@yike21 @chaunceyjiang can you take a look?

[yike21]

@yike21 @chaunceyjiang can you take a look?

Ok, I'll take a look at it ASAP :-)

[RainbowMango]

Here is the FlinkDeployment reference where you can find the definition of the status:
https://nightlies.apache.org/flink/flink-kubernetes-operator-docs-main/docs/custom-resource/reference/

[yike21]

/lgtm
Thanks a lot! @mszacillo

[RainbowMango]

Looks great!
/approve

[karmada-bot]

[APPROVALNOTIFIER] This PR is APPROVED

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