Make run.sh not overwrite genesis if existing (#7837)

run.sh

@@ -77,6 +77,9 @@ else
   solana-keygen new --no-passphrase -fso "$leader_storage_account_keypair"
 fi
 
+if [[ -e "$ledgerDir"/genesis.bin ]]; then
+  echo "Use existing genesis"
+else
   solana-genesis \
     --hashes-per-tick sleep \
     --faucet-pubkey "$dataDir"/faucet-keypair.json \
@@ -87,6 +90,7 @@ solana-genesis \
     --bootstrap-storage-pubkey "$dataDir"/leader-storage-account-keypair.json \
     --ledger "$ledgerDir" \
     --operating-mode development
+fi
 
 abort() {
   set +e