Fix dangling modified file on make devnet-up

When starting from a fresh clone of the repo and running

```
make
make cannon-prestate
make devnet-up
```

We are left with a file changed in the tree at

```
packages/contracts-bedrock/deploy-config/devnetL1.json
```

This file is a bit annoying as it should not be checked in but shows as
an outstanding change.  The python script reads the original file, backs
it up, then rewrites that file with a new timestamp.

I'm not entirely certain why the timestamp needs to be rewritten, so
I've left that modification in place.  Instead, this change takes the
approach of moving the original file to a 'template' path, and ignoring
the modified file.  In this way there's no longer any need to constantly
create a backup and have the changes show up in a git diff.

bedrock-devnet/devnet/__init__.py

@@ -56,8 +56,9 @@ def main():
     deployment_dir = pjoin(contracts_bedrock_dir, 'deployments', 'devnetL1')
     op_node_dir = pjoin(args.monorepo_dir, 'op-node')
     ops_bedrock_dir = pjoin(monorepo_dir, 'ops-bedrock')
-    deploy_config_dir = pjoin(contracts_bedrock_dir, 'deploy-config'),
-    devnet_config_path = pjoin(contracts_bedrock_dir, 'deploy-config', 'devnetL1.json')
+    deploy_config_dir = pjoin(contracts_bedrock_dir, 'deploy-config')
+    devnet_config_path = pjoin(deploy_config_dir, 'devnetL1.json')
+    devnet_config_template_path = pjoin(deploy_config_dir, 'devnetL1-template.json')
     ops_chain_ops = pjoin(monorepo_dir, 'op-chain-ops')
     sdk_dir = pjoin(monorepo_dir, 'packages', 'sdk')
 
@@ -69,6 +70,7 @@ def main():
       l1_deployments_path=pjoin(deployment_dir, '.deploy'),
       deploy_config_dir=deploy_config_dir,
       devnet_config_path=devnet_config_path,
+      devnet_config_template_path=devnet_config_template_path,
       op_node_dir=op_node_dir,
       ops_bedrock_dir=ops_bedrock_dir,
       ops_chain_ops=ops_chain_ops,
@@ -124,10 +126,16 @@ def deploy_contracts(paths):
         '--rpc-url', 'http://127.0.0.1:8545'
     ], env={}, cwd=paths.contracts_bedrock_dir)
 
-
+def init_devnet_l1_deploy_config(paths, update_timestamp=False):
+    deploy_config = read_json(paths.devnet_config_template_path)
+    if update_timestamp:
+        deploy_config['l1GenesisBlockTimestamp'] = '{:#x}'.format(int(time.time()))
+    write_json(paths.devnet_config_path, deploy_config)
 
 def devnet_l1_genesis(paths):
     log.info('Generating L1 genesis state')
+    init_devnet_l1_deploy_config(paths)
+
     geth = subprocess.Popen([
         'geth', '--dev', '--http', '--http.api', 'eth,debug',
         '--verbosity', '4', '--gcmode', 'archive', '--dev.gaslimit', '30000000'
@@ -157,13 +165,13 @@ def devnet_deploy(paths):
         if os.path.exists(paths.allocs_path) == False:
             devnet_l1_genesis(paths)
 
-        devnet_config_backup = pjoin(paths.devnet_dir, 'devnetL1.json.bak')
-        shutil.copy(paths.devnet_config_path, devnet_config_backup)
-        deploy_config = read_json(paths.devnet_config_path)
-        deploy_config['l1GenesisBlockTimestamp'] = '{:#x}'.format(int(time.time()))
-        write_json(paths.devnet_config_path, deploy_config)
+        # It's odd that we want to regenerate the devnetL1.json file with
+        # an updated timestamp different than the one used in the devnet_l1_genesis
+        # function.  But, without it, CI flakes on this test rather consistently.
+        # If someone reads this comment and understands why this is being done, please
+        # update this comment to explain.
+        init_devnet_l1_deploy_config(paths, update_timestamp=True)
         outfile_l1 = pjoin(paths.devnet_dir, 'genesis-l1.json')
-
         run_command([
             'go', 'run', 'cmd/main.go', 'genesis', 'l1',
             '--deploy-config', paths.devnet_config_path,

packages/contracts-bedrock/.gitignore

@@ -26,3 +26,6 @@ deployments/hardhat
 deployments/getting-started
 deployments/*/.deploy
 deployments/1337
+
+# Devnet config which changes with each 'make devnet-up'
+deploy-config/devnetL1.json