Reduce memory usage for diskann index

[xiaocai2333]

issue: #22140

[mergify[bot]]

@xiaocai2333 ut workflow job failed, comment rerun ut can trigger the job again.

[codecov[bot]]

Codecov Report

Merging #23600 (3c9fe1c) into master (ccba133) will decrease coverage by 0.34%. The diff coverage is 0.00%.

@@            Coverage Diff             @@
##           master   #23600      +/-   ##
==========================================
- Coverage   82.00%   81.67%   -0.34%     
==========================================
  Files         742      743       +1     
  Lines       96724    98782    +2058     
==========================================
+ Hits        79318    80677    +1359     
- Misses      14451    15150     +699     
  Partials     2955     2955              

Impacted Files	Coverage Δ
internal/core/src/storage/DiskFileManagerImpl.cpp	0.00% <0.00%> (ø)
internal/core/src/storage/DiskFileManagerImpl.h	0.00% <0.00%> (ø)

... and 166 files with indirect coverage changes

[mergify[bot]]

@xiaocai2333 E2e jenkins job failed, comment /run-cpu-e2e can trigger the job again.

[xiaocai2333]

/run-cpu-e2e

[xiaocai2333]

/run-cpu-e2e

[xiaocai2333]

/run-cpu-e2e

[xige-16]

/lgtm

[czs007]

/approve /lgtm

[sre-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: czs007, xiaocai2333

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