chore: deprecate KeepInvalidTxsInCache (#2623)

## Description

Fixes #2587

Author: ninabarbakadze

config/config.go

@@ -821,6 +821,7 @@ type MempoolConfig struct {
 	// Do not remove invalid transactions from the cache (default: false)
 	// Set to true if it's not possible for any invalid transaction to become
 	// valid again in the future.
+	// Deprecated: KeepInvalidTxsInCache is deprecated and will be removed in a future version.
 	KeepInvalidTxsInCache bool `mapstructure:"keep-invalid-txs-in-cache"`
 	// Maximum size of a single transaction
 	// NOTE: the max size of a tx transmitted over the network is {max_tx_bytes}.

config/toml.go

@@ -397,6 +397,7 @@ cache_size = {{ .Mempool.CacheSize }}
 # Do not remove invalid transactions from the cache (default: false)
 # Set to true if it's not possible for any invalid transaction to become valid
 # again in the future.
+# DEPRECATED: keep-invalid-txs-in-cache is deprecated and will be removed in a future version.
 keep-invalid-txs-in-cache = {{ .Mempool.KeepInvalidTxsInCache }}
 
 # Maximum size of a single transaction.