Switching to use buildx to build docker images #2270

Job	Run time
Basic Checks	3m 4s
Unit Tests	6m 11s
Integration Tests (raft)	11m 36s
Integration Tests (pvtdata)	20m 46s
Integration Tests (pvtdatapurge)	5m 6s
Integration Tests (ledger)	16m 36s
Integration Tests (lifecycle)	12m 56s
Integration Tests (e2e smartbft)	17m 32s
Integration Tests (discovery gossip devmode pluggable)	5m 12s
Integration Tests (gateway idemix pkcs11 configtx configtxlator)	11m 17s
Integration Tests (sbe nwo msp)	10m 26s
	2h 0m 42s

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