Skip node level throttle during server bootstrap - Enhancement

[deepthi912]

Fix for the following issue:
#12742

Instead of throttling server for rate limitting while server bootstrap, enable it just before server starts executing queries for maximum CPU utilization.

[xiangfu0]

lgtm

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 0% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 27.91%. Comparing base (59551e4) to head (77bd980).
Report is 310 commits behind head on master.

Files	Patch %	Lines
.../pinot/server/starter/helix/BaseServerStarter.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##             master   #12930       +/-   ##
=============================================
- Coverage     61.75%   27.91%   -33.84%     
+ Complexity      207      192       -15     
=============================================
  Files          2436     2502       +66     
  Lines        133233   136388     +3155     
  Branches      20636    21106      +470     
=============================================
- Hits          82274    38070    -44204     
- Misses        44911    95417    +50506     
+ Partials       6048     2901     -3147     

Flag	Coverage Δ
custom-integration1	?
integration	?
integration1	?
integration2	?
java-11	?
java-21	27.91% <0.00%> (-33.72%)	⬇️
skip-bytebuffers-false	27.91% <0.00%> (-33.84%)	⬇️
skip-bytebuffers-true	?
temurin	27.91% <0.00%> (-33.84%)	⬇️
unittests	27.91% <0.00%> (-33.84%)	⬇️
unittests1	?
unittests2	27.91% <0.00%> (+0.18%)	⬆️

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[npawar]

This doesn't seem to be the right fix.. If you look at line https://github.com/apache/pinot/pull/12930/files#diff-f99e2a5e74a22eaa5a052fce00e6b265418fb6b419969de16976bb405ec11a65R649, the throttling is actually not enabled until that point. So this should have already been working as expected.
If the issue reporter is seeing that it's not working, we need to instead investgate why the enableThrottling isn't working as expected. Perhaps add some logs and try to observe during startup, when the throttling actually kicks in, and confirm if this is an issue or not.

[deepthi912]

I totally missed enableThrottling flag. I can try adding more logs locally and see when the throttling is kicking in to identify the grey area if present.