fix(timer): cache bus writer for deliver

[hwjiangkai]

Signed-off-by: jyjiangkai jyjiangkai@163.com

What problem does this PR solve?

Issue Number: close #xxx

Problem Summary

What is changed and how does it work?

Check List

Tests

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

[codecov]

Codecov Report

Merging #415 (fe63faa) into main (09f3748) will decrease coverage by 3.14%.
The diff coverage is 50.07%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #415      +/-   ##
==========================================
- Coverage   62.72%   59.58%   -3.14%     
==========================================
  Files         133      175      +42     
  Lines       12128    14369    +2241     
==========================================
+ Hits         7607     8562     +955     
- Misses       3977     5194    +1217     
- Partials      544      613      +69     

Impacted Files	Coverage Δ
internal/controller/eventbus/server/instance.go	72.04% <ø> (ø)
internal/controller/trigger/storage/secret.go	48.48% <ø> (ø)
...nternal/controller/trigger/storage/subscription.go	54.71% <ø> (ø)
...ernal/controller/trigger/storage/trigger_worker.go	63.41% <ø> (ø)
...rnal/primitive/interceptor/errinterceptor/error.go	0.00% <0.00%> (ø)
.../primitive/interceptor/memberinterceptor/member.go	0.00% <0.00%> (ø)
internal/primitive/vanus/id.go	19.68% <0.00%> (-0.65%)	⬇️
internal/raft/log/recovery.go	52.27% <ø> (ø)
internal/raft/log/wal.go	100.00% <ø> (ø)
internal/store/block/entry.go	70.96% <ø> (ø)
... and 156 more

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[wenfengwang]

LGTM