mempool: fix clearing completed tx cache

[afalaleev]

No description provided.

[neonlabstech]

Solana Requests Statistics

	count	min_time	max_time	average_time	median_time
getAccountInfo	62315	0	0.243	0.000793822	0
getSlot	61021	0	0.239	0.000493748	0
getBlocks	27244	0	0.098	0.000434224	0
getMultipleAccounts	14915	0	0.162	0.00216614	0.001
getBlock	13781	0	0.039	0.00112539	0.001
getTransaction	10142	0	0.321	0.0124287	0.004
getLatestBlockhash	10119	0	0.131	0.00249195	0.001
getBlockTime	6280	0	0.088	0.000494268	0
sendTransaction	5264	0	0.24	0.0119234	0.006
getBalance	1788	0	0.241	0.00108725	0.001
getSignatureStatuses	1162	0	0.12	0.000841652	0
getVersion	604	0	0.026	0.000680464	0
isBlockhashValid	563	0	0.024	0.000452931	0
simulateTransaction	491	0	0.008	0.00172098	0.001
getSignaturesForAddress	60	0	0.004	0.00173333	0.002
requestAirdrop	32	0	0.001	0.00078125	0.001
getHealth	3	0	0.001	0.000333333	0
getTokenAccountBalance	3	0	0	0	0
getFirstAvailableBlock	2	0.001	0.001	0.001	0.001
getMinimumBalanceForRentExemption	1	0	0	0	0
getClusterNodes	1	0	0	0	0