fix: remove the deprecated pow from RewardsManager (OZ N-03)

Author: pcarranzav

.solhintignore

@@ -4,6 +4,5 @@ node_modules
 ./contracts/discovery/erc1056
 ./contracts/rewards/RewardsManager.sol
 ./contracts/staking/libs/LibFixedMath.sol
-./contracts/tests/RewardsManagerMock.sol
 ./contracts/tests/ens
 ./contracts/tests/testnet/GSRManager.sol

contracts/rewards/RewardsManager.sol

@@ -424,67 +424,4 @@ contract RewardsManager is RewardsManagerV4Storage, GraphUpgradeable, IRewardsMa
 
         return rewards;
     }
-
-    /**
-     * @dev Raises x to the power of n with scaling factor of base.
-     * Based on: https://github.com/makerdao/dss/blob/master/src/pot.sol#L81
-     * @param x Base of the exponentiation
-     * @param n Exponent
-     * @param base Scaling factor
-     * @return z Exponential of n with base x
-     */
-    function _pow(
-        uint256 x,
-        uint256 n,
-        uint256 base
-    ) private pure returns (uint256 z) {
-        assembly {
-            switch x
-            case 0 {
-                switch n
-                case 0 {
-                    z := base
-                }
-                default {
-                    z := 0
-                }
-            }
-            default {
-                switch mod(n, 2)
-                case 0 {
-                    z := base
-                }
-                default {
-                    z := x
-                }
-                let half := div(base, 2) // for rounding.
-                for {
-                    n := div(n, 2)
-                } n {
-                    n := div(n, 2)
-                } {
-                    let xx := mul(x, x)
-                    if iszero(eq(div(xx, x), x)) {
-                        revert(0, 0)
-                    }
-                    let xxRound := add(xx, half)
-                    if lt(xxRound, xx) {
-                        revert(0, 0)
-                    }
-                    x := div(xxRound, base)
-                    if mod(n, 2) {
-                        let zx := mul(z, x)
-                        if and(iszero(iszero(x)), iszero(eq(div(zx, x), z))) {
-                            revert(0, 0)
-                        }
-                        let zxRound := add(zx, half)
-                        if lt(zxRound, zx) {
-                            revert(0, 0)
-                        }
-                        z := div(zxRound, base)
-                    }
-                }
-            }
-        }
-    }
 }

contracts/tests/RewardsManagerMock.sol

@@ -9,7 +9,6 @@ import { Curation } from '../../build/types/Curation'
 import { EpochManager } from '../../build/types/EpochManager'
 import { GraphToken } from '../../build/types/GraphToken'
 import { RewardsManager } from '../../build/types/RewardsManager'
-import { RewardsManagerMock } from '../../build/types/RewardsManagerMock'
 import { Staking } from '../../build/types/Staking'
 
 import {
@@ -48,7 +47,6 @@ describe('Rewards', () => {
   let epochManager: EpochManager
   let staking: Staking
   let rewardsManager: RewardsManager
-  let rewardsManagerMock: RewardsManagerMock
 
   // Derive some channel keys for each indexer used to sign attestations
   const channelKey1 = deriveChannelKey()
@@ -140,11 +138,6 @@ describe('Rewards', () => {
       governor.signer,
     ))
 
-    rewardsManagerMock = (await deployContract(
-      'RewardsManagerMock',
-      governor.signer,
-    )) as unknown as RewardsManagerMock
-
     // 200 GRT per block
     await rewardsManager.connect(governor.signer).setIssuancePerBlock(ISSUANCE_PER_BLOCK)
 
@@ -831,18 +824,6 @@ describe('Rewards', () => {
     })
   })
 
-  describe('pow', function () {
-    it('exponentiation works under normal boundaries (annual rate from 1% to 700%, 90 days period)', async function () {
-      const baseRatio = toGRT('0.000000004641377923') // 1% annual rate
-      const timePeriods = (60 * 60 * 24 * 10) / 15 // 90 days in blocks
-      for (let i = 0; i < 50; i = i + 4) {
-        const r = baseRatio.mul(i * 4).add(toGRT('1'))
-        const h = await rewardsManagerMock.pow(r, timePeriods, toGRT('1'))
-        console.log('\tr:', formatGRT(r), '=> c:', formatGRT(h))
-      }
-    })
-  })
-
   describe('edge scenarios', function () {
     it('close allocation on a subgraph that no longer have signal', async function () {
       // Update total signalled