feat: remove `fip-0115` feature flag (#6948) #20070

Job	Run time
Build Ubuntu	6m 54s
Calibnet RPC checks	4s
Build MacOS	13m 10s
Calibnet no discovery checks	1m 45s
State migrations	3m 47s
Calibnet check	17m 13s
Forest CLI checks	10m 56s
Calibnet stateless mode check	2m 4s
Calibnet stateless RPC check	2m 24s
Calibnet kademlia checks	2m 35s
Devnet checks	6m 23s
Bootstrap checks - Lotus	5m 30s
Bootstrap checks - Forest	3m 30s
db-migration-checks	7m 51s
Calibnet eth mapping check	5m 10s
Calibnet api test-stateful check	5m 55s
Wallet tests	1m 41s
Calibnet RPC checks	0s
Diff snapshot export checks	0s
V1 snapshot export checks	0s
Additional integration tests status	0s
V2 snapshot export checks	0s
Delegated wallet tests	0s
Integration tests status	0s
	1h 36m 52s

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