chore: use symlink for flatten.sh #9541

Job	Run time
Cancel Outdated Jobs	4s
changes	24s
Foundry Gas Snapshot (contracts-core)	6m 27s
Foundry Gas Snapshot (contracts-rfq)	3m 18s
Slither (contracts-core)	4m 21s
Foundry Gas Snapshot (contracts-communication)	3m 24s
Foundry Coverage (contracts-core)	19m 50s
Foundry Coverage (contracts-rfq)	3m 56s
Slither (contracts-rfq)	5m 38s
Deploy Docs (contracts-core)	2m 42s
Foundry Coverage (contracts-communication)	3m 27s
Slither (contracts-communication)	4m 48s
Deploy Docs (contracts-rfq)	2m 30s
Deploy Docs (contracts-communication)	2m 33s
Foundry Size Check (contracts-core)	4m 26s
Foundry Size Check (contracts-rfq)	2m 57s
Foundry Size Check (contracts-communication)	4m 20s
	1h 15m 5s

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