fix(scheduler): sync instance info memory leak

[Muzry]

What type of this PR

Add one of the following kinds:
/kind bug

What this PR does / why we need it:

• fix(scheduler): sync instance info memory leak

Which issue(s) this PR fixes:

• Fixes #your-issue_number
• [Erda Cloud Issue Link](paste your link here)

Specified Reviewers:

/assign @luobily @sixther-dc

ChangeLog

Language	Changelog
🇺🇸 English	fix(scheduler): sync instance info memory leak
🇨🇳 中文	修复获取实例列表内存泄漏的问题

Need cherry-pick to release versions?

Add comment like /cherry-pick release/1.0 when this PR is merged.

For details on the cherry pick process, see the cherry pick requests section under CONTRIBUTING.md.

[codecov]

Codecov Report

Merging #1485 (c737b7b) into master (f74c0e4) will increase coverage by 0.00%.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1485   +/-   ##
=======================================
  Coverage   12.17%   12.18%           
=======================================
  Files        1007     1007           
  Lines      105142   105143    +1     
=======================================
+ Hits        12805    12807    +2     
+ Misses      91138    91137    -1     
  Partials     1199     1199           

Impacted Files	Coverage Δ
modules/scheduler/executor/plugins/k8s/k8s.go	1.43% <ø> (+0.31%)	⬆️

[sixther-dc]

/lgtm

[sfwn]

/approve

[Muzry]

/cherry-pick release/1.2