Report lost_insertions metrics correctly

[ryoqun]

Problem

loaded-programs-cache-stats.lost_insertions is wrongly reporting its value using insertions, introduced at #35026 (comment).

Summary of Changes

Use correct lost_insertions instead.

Maybe worth to bp to v1.18 and v1.17?

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (897adb2) 81.6% compared to head (57e26dd) 81.6%.

Additional details and impacted files

@@            Coverage Diff            @@
##           master   #35191     +/-   ##
=========================================
- Coverage    81.6%    81.6%   -0.1%     
=========================================
  Files         833      833             
  Lines      224827   224827             
=========================================
- Hits       183523   183518      -5     
- Misses      41304    41309      +5     

[mergify]

Backports to the stable branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule.

[mergify]

Backports to the beta branch are to be avoided unless absolutely necessary for fixing bugs, security issues, and perf regressions. Changes intended for backport should be structured such that a minimum effective diff can be committed separately from any refactoring, plumbing, cleanup, etc that are not strictly necessary to achieve the goal. Any of the latter should go only into master and ride the normal stabilization schedule. Exceptions include CI/metrics changes, CLI improvements and documentation updates on a case by case basis.