chore: add more sequencers to staging-public (#17681)

Backport of #17679

Author: alexghr

spartan/environments/staging-public.env

@@ -25,6 +25,9 @@ SPONSORED_FPC=true
 SEQ_MIN_TX_PER_BLOCK=0
 SEQ_MAX_TX_PER_BLOCK=8
 
+VALIDATOR_REPLICAS=5
+VALIDATORS_PER_NODE=16
+
 BOT_TRANSFERS_REPLICAS=1
 BOT_TRANSFERS_TX_INTERVAL_SECONDS=250
 BOT_TRANSFERS_FOLLOW_CHAIN=PENDING
@@ -39,4 +42,7 @@ RPC_INGRESS_STATIC_IP_NAME=staging-public-rpc-ip
 RPC_INGRESS_SSL_CERT_NAME=staging-public-rpc-cert
 
 FLUSH_ENTRY_QUEUE=false
-CREATE_ROLLUP_CONTRACTS=false
+CREATE_ROLLUP_CONTRACTS=false
+
+VALIDATOR_INDICES=$(seq -s, 1 80)
+VALIDATOR_MNEMONIC_START_INDEX=1