test: add regression test of pubsub and timer

[wenfengwang]

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary

add regression test of pubsub

What is changed and how does it work?

program sends events to eventbus

1. create an eventbus
2. create a subscription
3. start events sending
4. start events receiving
5. check if received all events in next 30s after sending finished

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

[codecov]

Codecov Report

Merging #413 (e679d94) into main (2a78cb5) will decrease coverage by 0.53%.
The diff coverage is 29.46%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #413      +/-   ##
==========================================
- Coverage   57.71%   57.18%   -0.53%     
==========================================
  Files         180      182       +2     
  Lines       14614    14912     +298     
==========================================
+ Hits         8434     8527      +93     
- Misses       5552     5753     +201     
- Partials      628      632       +4     

Impacted Files	Coverage Δ
...ernal/controller/trigger/validation/subscripton.go	69.29% <ø> (+0.85%)	⬆️
internal/gateway/proxy/deadletter.go	0.00% <0.00%> (ø)
internal/gateway/proxy/direct.go	73.33% <0.00%> (-5.24%)	⬇️
internal/gateway/proxy/proxy.go	24.67% <0.00%> (-0.42%)	⬇️
internal/store/segment/server.go	14.07% <0.00%> (-0.06%)	⬇️
internal/trigger/client/gcloud_functions.go	0.00% <0.00%> (ø)
internal/trigger/client/grpc.go	0.00% <0.00%> (ø)
internal/trigger/client/http.go	0.00% <0.00%> (ø)
internal/trigger/client/interface.go	0.00% <0.00%> (-19.24%)	⬇️
internal/trigger/client/lambda.go	0.00% <0.00%> (ø)
... and 18 more

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