feat: set startup probe to prevent from unnecessary restarts

[arkbriar]

What's changed and what's your intention?

PLEASE DO NOT LEAVE THIS EMPTY !!!

Please explain IN DETAIL what the changes are in this PR and why they are needed:

• As title. Using startup probe can prevent pods from restarting when meta isn't fully initialized. It helps bootstrapping a RisingWave cluster more smoothly.
• Note that this is a change that will affect existing clusters: after any kind of manifest operations, all RisingWave pods will get recreated.

Checklist

• I have written the necessary docs and comments
• I have added necessary unit tests and integration tests

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Merging #490 (a9b978c) into main (5bd9701) will increase coverage by 0.07%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main     #490      +/-   ##
==========================================
+ Coverage   67.67%   67.74%   +0.07%     
==========================================
  Files          27       27              
  Lines        4210     4220      +10     
==========================================
+ Hits         2849     2859      +10     
  Misses       1312     1312              
  Partials       49       49              

Flag	Coverage Δ
unittests	67.74% <100.00%> (+0.07%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files Changed	Coverage Δ
pkg/factory/risingwave_object_factory.go	89.63% <100.00%> (+0.07%)	⬆️

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[wjf3121]

LGTM!

[Gogomoe]

LGTM!