fix: api: compute gasUsedRatio based on max gas in the tipset (fileco…

…in-project#11354)

We were computing this based on the max block gas, but this is
incorrect. The new value isn't entirely correct either (we should
probably compute an average of the gas used in each block in the
tipset?), but it's good enough.

fixes filecoin-project#10515

node/impl/full/eth.go

@@ -733,10 +733,11 @@ func (a *EthModule) EthFeeHistory(ctx context.Context, p jsonrpc.RawParams) (eth
 		}
 
 		rewards, totalGasUsed := calculateRewardsAndGasUsed(rewardPercentiles, txGasRewards)
+		maxGas := build.BlockGasLimit * int64(len(ts.Blocks()))
 
 		// arrays should be reversed at the end
 		baseFeeArray = append(baseFeeArray, ethtypes.EthBigInt(basefee))
-		gasUsedRatioArray = append(gasUsedRatioArray, float64(totalGasUsed)/float64(build.BlockGasLimit))
+		gasUsedRatioArray = append(gasUsedRatioArray, float64(totalGasUsed)/float64(maxGas))
 		rewardsArray = append(rewardsArray, rewards)
 		oldestBlkHeight = uint64(ts.Height())
 		blocksIncluded++