enhance: [2.5] Move forward l0 logic out of delta lock (#37337)

[congqixia]

Cherry pick from master
pr: #37337
Related to #35303

deleteMut shall be protecting streaming delete buffer, forward l0 could be move out of the rlock section to reduce tsafe impact from loading segments.

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: congqixia

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/querynodev2/delegator/OWNERS [congqixia]

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

[mergify]

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

[codecov]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 80.83%. Comparing base (3e4dbd9) to head (7bbdc24).
Report is 5 commits behind head on 2.5.

Files with missing lines	Patch %	Lines
internal/querynodev2/delegator/delegator_data.go	57.14%	2 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              2.5   #37398      +/-   ##
==========================================
- Coverage   83.09%   80.83%   -2.26%     
==========================================
  Files        1032     1322     +290     
  Lines      157808   183237   +25429     
==========================================
+ Hits       131130   148125   +16995     
- Misses      21479    29907    +8428     
- Partials     5199     5205       +6     

Components	Coverage Δ
Client	∅ <ø> (∅)
Core	66.92% <ø> (∅)
Go	83.10% <57.14%> (-0.02%)	⬇️

Files with missing lines	Coverage Δ
internal/querynodev2/delegator/delegator_data.go	84.74% <57.14%> (+0.05%)	⬆️

... and 312 files with indirect coverage changes

[congqixia]

/run-cpu-e2e

[mergify]

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

[congqixia]

/run-cpu-e2e

[mergify]

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

[congqixia]

/run-cpu-e2e

[mergify]

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

[congqixia]

/run-cpu-e2e

[mergify]

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

[congqixia]

/run-cpu-e2e

[mergify]

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