fix: Fix subscription leak

[bigsheeper]

Close (unsubscribe) the msg stream after completing the PreCreatedTopic check to prevent backlog issue.

issue: #36021

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: bigsheeper
To complete the pull request process, please assign yanliang567 after the PR has been reviewed.
You can assign the PR to them by writing /assign @yanliang567 in a comment when ready.

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

Needs approval from an approver in each of these files:

• internal/rootcoord/OWNERS

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

Attention: Patch coverage is 71.42857% with 4 lines in your changes missing coverage. Please review.

Project coverage is 83.26%. Comparing base (aed3b94) to head (02b2d66).
Report is 8 commits behind head on master.

Files with missing lines	Patch %	Lines
internal/rootcoord/dml_channels.go	71.42%	2 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #37382      +/-   ##
==========================================
+ Coverage   81.03%   83.26%   +2.22%     
==========================================
  Files        1305     1015     -290     
  Lines      183190   157818   -25372     
==========================================
- Hits       148455   131412   -17043     
+ Misses      29533    21210    -8323     
+ Partials     5202     5196       -6     

Components	Coverage Δ
Client	∅ <ø> (∅)
Core	∅ <ø> (∅)
Go	83.29% <71.42%> (+0.02%)	⬆️

Files with missing lines	Coverage Δ
internal/rootcoord/dml_channels.go	96.62% <71.42%> (-1.47%)	⬇️

... and 320 files with indirect coverage changes

[mergify]

@bigsheeper E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[bigsheeper]

/run-cpu-e2e

[mergify]

@bigsheeper E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[bigsheeper]

/run-cpu-e2e

[mergify]

@bigsheeper E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[mergify]

@bigsheeper go-sdk check failed, comment rerun go-sdk can trigger the job again.

[mergify]

@bigsheeper cpp-unit-test check failed, comment rerun cpp-unit-test can trigger the job again.

[bigsheeper]

rerun cpp-unit-test

[bigsheeper]

rerun go-sdk

[mergify]

@bigsheeper cpp-unit-test check failed, comment rerun cpp-unit-test can trigger the job again.

[bigsheeper]

rerun cpp-unit-test

[mergify]

@bigsheeper go-sdk check failed, comment rerun go-sdk can trigger the job again.

[mergify]

@bigsheeper cpp-unit-test check failed, comment rerun cpp-unit-test can trigger the job again.

[bigsheeper]

rerun cpp-unit-test