revert(ci): e2e timeout 15 -> 17

[xiangjinwu]

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What's changed and what's your intention?

CI e2e timeout was bumped from 15m to 17m in #12858, on suspicion that there was perf regression #12825. It ran consistently slower (batch taking 8m50s) during 2023-10-20T15:06Z - 2023-10-21T07:27Z but came back to 7m30s after that.

https://buildkite.com/risingwavelabs/pull-request/builds/33837
https://buildkite.com/risingwavelabs/pull-request/builds/33835
https://buildkite.com/risingwavelabs/pull-request/builds/33834

Ideally there should be no such ci performance fluctuation. Still no clue what happend.

At the same time started an attempt to reduce test time #12984

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[codecov]

Codecov Report

Merging #12985 (9e4050b) into main (19643ad) will increase coverage by 0.01%.
Report is 9 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #12985      +/-   ##
==========================================
+ Coverage   68.78%   68.79%   +0.01%     
==========================================
  Files        1495     1495              
  Lines      250092   250092              
==========================================
+ Hits       172014   172052      +38     
+ Misses      78078    78040      -38     

Flag	Coverage Δ
rust	68.79% <ø> (+0.01%)	⬆️

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[xiangjinwu]

8m40s again 😂

[xxchan]

It seems there has been fluctuation for a while, but it's not clear what's wrong. 😟 Maybe we need more fine-grained monitoring for CI to know regression better.

[xiangjinwu]

@hzxa21 Are the sleeps necessary given we already enabled implicit flush?

[hzxa21]

table size is propagated to frontend through async notification. I think a sleep is still needed since a successful flush doesn't mean the notification is received by frontend. But 30s sleep seems too long. We can make it 3s I think.

[huangjw806]

LGTM!