fix Background Goroutines Cannot Exit Gracefully

[WyRainBow]

fix #992

[codecov-commenter]

Codecov Report

:x: Patch coverage is 57.50000% with 17 lines in your changes missing coverage. Please review. :white_check_mark: Project coverage is 56.82%. Comparing base (b18bcb0) to head (e5b4134).

Files with missing lines	Patch %	Lines
pkg/datasource/sql/datasource/base/meta_cache.go	48.38%	15 Missing and 1 partial :warning:
pkg/datasource/sql/at_resource_manager.go	0.00%	1 Missing :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #996      +/-   ##
==========================================
+ Coverage   56.49%   56.82%   +0.33%     
==========================================
  Files         266      266              
  Lines       17484    17494      +10     
==========================================
+ Hits         9877     9941      +64     
+ Misses       6772     6720      -52     
+ Partials      835      833       -2     

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[WyRainBow]

Perhaps you could clone the samples repository and replace its "seata go" dependency with your modified local version to verify if it works correctly.

Verified by cloning apache/seata-go-samples, replacing the dependency with my local incubator-seata-go via go mod edit -replace ..., running go mod tidy, and all go test ./... runs succeeded on both the samples repo and the main repo.

[tew-axiom]

Plz check and resolve the conflicts.

[LucienShen-Liu]

Hi, please fix the CI when you have time.