contracts-bedrock: delete dead SystemConfig code

packages/contracts-bedrock/.gas-snapshot

@@ -418,7 +418,7 @@ SequencerFeeVault_Test:test_withdraw_succeeds() (gas: 163228)
 SetPrevBaseFee_Test:test_setPrevBaseFee_succeeds() (gas: 11515)
 StandardBridge_Stateless_Test:test_isCorrectTokenPair_succeeds() (gas: 49936)
 StandardBridge_Stateless_Test:test_isOptimismMintableERC20_succeeds() (gas: 33072)
-SystemConfig_Initialize_TestFail:test_initialize_lowGasLimit_reverts() (gas: 148858)
+SystemConfig_Initialize_TestFail:test_initialize_lowGasLimit_reverts() (gas: 148848)
 SystemConfig_Setters_TestFail:test_setBatcherHash_notOwner_reverts() (gas: 10546)
 SystemConfig_Setters_TestFail:test_setGasConfig_notOwner_reverts() (gas: 10622)
 SystemConfig_Setters_TestFail:test_setGasLimit_notOwner_reverts() (gas: 10615)
@@ -427,6 +427,6 @@ SystemConfig_Setters_TestFail:test_setResourceConfig_badPrecision_reverts() (gas
 SystemConfig_Setters_TestFail:test_setResourceConfig_lowGasLimit_reverts() (gas: 16082)
 SystemConfig_Setters_TestFail:test_setResourceConfig_notOwner_reverts() (gas: 11790)
 SystemConfig_Setters_TestFail:test_setResourceConfig_zeroDenominator_reverts() (gas: 13039)
-SystemConfig_Setters_TestFail:test_setUnsafeBlockSigner_notOwner_reverts() (gas: 10639)
+SystemConfig_Setters_TestFail:test_setUnsafeBlockSigner_notOwner_reverts() (gas: 10616)
 TransferOnionTest:test_constructor_succeeds() (gas: 564855)
 TransferOnionTest:test_unwrap_succeeds() (gas: 724958)

packages/contracts-bedrock/contracts/L1/SystemConfig.sol

@@ -42,13 +42,6 @@ contract SystemConfig is OwnableUpgradeable, Semver {
      */
     bytes32 public constant UNSAFE_BLOCK_SIGNER_SLOT = keccak256("systemconfig.unsafeblocksigner");
 
-    /**
-     * @notice Minimum gas limit. This should not be lower than the maximum deposit gas resource
-     *         limit in the ResourceMetering contract used by OptimismPortal, to ensure the L2
-     *         block always has sufficient gas to process deposits.
-     */
-    uint64 public constant MINIMUM_GAS_LIMIT = 8_000_000;
-
     /**
      * @notice Fixed L2 gas overhead. Used as part of the L2 fee calculation.
      */
@@ -87,7 +80,7 @@ contract SystemConfig is OwnableUpgradeable, Semver {
     event ConfigUpdate(uint256 indexed version, UpdateType indexed updateType, bytes data);
 
     /**
-     * @custom:semver 1.1.0
+     * @custom:semver 1.2.0
      *
      * @param _owner             Initial owner of the contract.
      * @param _overhead          Initial overhead value.
@@ -105,7 +98,7 @@ contract SystemConfig is OwnableUpgradeable, Semver {
         uint64 _gasLimit,
         address _unsafeBlockSigner,
         ResourceMetering.ResourceConfig memory _config
-    ) Semver(1, 1, 0) {
+    ) Semver(1, 2, 0) {
         initialize({
             _owner: _owner,
             _overhead: _overhead,

packages/contracts-bedrock/contracts/test/SystemConfig.t.sol

@@ -176,7 +176,7 @@ contract SystemConfig_Setters_Test is SystemConfig_Init {
     }
 
     function testFuzz_setGasLimit_succeeds(uint64 newGasLimit) external {
-        uint64 minimumGasLimit = sysConf.MINIMUM_GAS_LIMIT();
+        uint64 minimumGasLimit = sysConf.minimumGasLimit();
         newGasLimit = uint64(
             bound(uint256(newGasLimit), uint256(minimumGasLimit), uint256(type(uint64).max))
         );

packages/contracts-bedrock/contracts/test/invariants/SystemConfig.t.sol

@@ -42,6 +42,6 @@ contract SystemConfig_GasLimitLowerBound_Invariant is Test {
      * than the hard-coded lower bound.
      */
     function invariant_gasLimitLowerBound() external {
-        assertTrue(config.gasLimit() >= config.MINIMUM_GAS_LIMIT());
+        assertTrue(config.gasLimit() >= config.minimumGasLimit());
     }
 }