Better buckets for storage proof size metrics

[jancionear]

In #11000 I added some metrics for the size of receipt/chunk storage proofs, along with upper bound estimation of those sizes. The buckets chosen in the PR weren't that good, as I didn't know what sort of values to expect.
I have spent some time looking at the data and I'd like to adjust the buckets to better fit the data distribution.

• Most receipts generate < 100KB of storage proof, so for receipt-level sizes I'd like to use a few small buckets and then some more big buckets to catch the big outliers.
• Chunk level proofs are usually within 2-6MB, so I changed the metric to use buckets between 0 and 15MB with 500KB increases
• The ratio for receipts was sometimes extremely high. I think it was due to small receipts (a receipt which writes little, but removes two nodes could easily shoot up to 50x ratio). Small receipts don't matter for the hard per receipt limit, so I excluded them from the metric to keep the values reasonable.

You can see how the new metrics look like here: https://nearinc.grafana.net/d/edbl9ztm5h1q8b/stateless-validation?orgId=1&var-chain_id=mainnet&var-shard_id=All&var-node_id=ci-b20a9aef-mainnet-rpc-europe-west4-01-84346caf&from=now-15m&to=now

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 71.11%. Comparing base (bd80b1d) to head (52581a8).
Report is 3 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #11075      +/-   ##
==========================================
- Coverage   71.24%   71.11%   -0.13%     
==========================================
  Files         760      761       +1     
  Lines      152630   152865     +235     
  Branches   152630   152865     +235     
==========================================
- Hits       108739   108714      -25     
- Misses      39454    39713     +259     
- Partials     4437     4438       +1     

Flag	Coverage Δ
backward-compatibility	0.24% <0.00%> (-0.01%)	⬇️
db-migration	0.24% <0.00%> (-0.01%)	⬇️
genesis-check	1.43% <0.00%> (-0.01%)	⬇️
integration-tests	36.85% <100.00%> (+0.03%)	⬆️
linux	69.59% <73.68%> (-0.13%)	⬇️
linux-nightly	70.61% <100.00%> (-0.13%)	⬇️
macos	54.28% <73.68%> (-0.10%)	⬇️
pytests	1.66% <0.00%> (-0.01%)	⬇️
sanity-checks	1.45% <0.00%> (-0.01%)	⬇️
unittests	66.79% <73.68%> (-0.13%)	⬇️
upgradability	0.29% <0.00%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.