v3.0: Sort in **descending** stake order (backport of #8787)

[mergify]

Problem

• stake-weighted sorting with some randomness was doing it backward
  • ignore randomness for now, assume rng always return 0.5
  • 2 nodes, stake=1, stake=2
  • weights = 0.5^(1/1) = 0.5
  • weights = 0.5^(1/2) = 0.707
  • node with stake 2 would come 2nd in list

Summary of Changes

• reverse the sort comparison

Fixes #

---

This is an automatic backport of pull request #8787 done by [Mergify](https://mergify.com).

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.4%. Comparing base (3454667) to head (2036d12).

Additional details and impacted files

@@           Coverage Diff           @@
##             v3.0    #8805   +/-   ##
=======================================
  Coverage    83.4%    83.4%           
=======================================
  Files         810      810           
  Lines      366213   366213           
=======================================
+ Hits       305677   305701   +24     
+ Misses      60536    60512   -24     

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[t-nelson]

out of an abundance of caution, we want to see this on testnet for a bit before accepting this one

[bw-solana]

@AshwinSekar @OliverNChalk - can we check metrics from testnet?

[OliverNChalk]

Here's the "raw" optimistic confirmation lag for last ~15 days:

With a 20 slot ema (although im not sure how much i rust influx):

Trend seems to be downwards...

[bw-solana]

it at least doesn't seem to be adversely affected. Still a minority of stake on v3.1 (~25%), so wouldn't expect differences to be too pronounced

[t-nelson]

it at least doesn't seem to be adversely affected. Still a minority of stake on v3.1 (~25%), so wouldn't expect differences to be too pronounced

doesn't this affect block inclusion so we should see higher staked votes landing earlier in upgraded nodes?

[OliverNChalk]

Yeah, I think we're expecting confirmation lag to trend downwards which it appears to (marginally).

[bw-solana]

doesn't this affect block inclusion so we should see higher staked votes landing earlier in upgraded nodes?

In theory, yes, but spot checking a few slots from 141vSYKGRPNGieSrGJy8EeDVBcbjSr6aWkimNgrNZ6xN, things still seem pretty random.

I'm assuming we're sorting properly within vote storage, but latency into the scheduler likely still dominates as vote storage remains small (not sure if we have a metric that can confirm this)

[t-nelson]

how does the trend look this week. should be more adoption by now

[t-nelson]

received offline confirmation that this is in fact effective