Fix multiSave childTask failed to etcd

[xige-16]

fix issue: #9787
Signed-off-by: xige-16 xi.ge@zilliz.com

[xiaofan-luan]

/approve
/lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: xiaofan-luan, xige-16

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• internal/querycoord/OWNERS [xiaofan-luan]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[codecov]

Codecov Report

Merging #10340 (4f216a0) into master (f940825) will increase coverage by 0.03%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master   #10340      +/-   ##
==========================================
+ Coverage   78.95%   78.98%   +0.03%     
==========================================
  Files         437      437              
  Lines       54572    54579       +7     
==========================================
+ Hits        43087    43110      +23     
+ Misses       9319     9309      -10     
+ Partials     2166     2160       -6     

Impacted Files	Coverage Δ
internal/querycoord/task_scheduler.go	75.00% <100.00%> (+0.26%)	⬆️
internal/rootcoord/proxy_manager.go	78.22% <0.00%> (-3.23%)	⬇️
internal/querycoord/querynode.go	66.39% <0.00%> (-1.64%)	⬇️
internal/querycoord/query_coord.go	76.25% <0.00%> (-1.37%)	⬇️
internal/indexnode/indexnode.go	89.95% <0.00%> (-1.21%)	⬇️
internal/msgstream/mq_msgstream.go	78.21% <0.00%> (-0.88%)	⬇️
...ternal/util/rocksmq/server/rocksmq/rocksmq_impl.go	75.41% <0.00%> (+0.16%)	⬆️
internal/datanode/data_node.go	84.59% <0.00%> (+0.61%)	⬆️
internal/util/flowgraph/node.go	73.39% <0.00%> (+0.91%)	⬆️
... and 5 more