Github CI: Test CI to reduce build time with matrix concurrency #655

Job	Run time
rustfmt	43s
clippy	27s
test (node/cli)	29s
test (node/rpc)	26s
test (node/inspect)	24s
test (node/testing)	25s
test (pallets/asset)	28s
test (pallets/chain-space)	35s
test (pallets/did)	24s
test (pallets/did-name)	26s
test (pallets/identity)	24s
test (pallets/network-membership)	28s
test (pallets/network-score)	23s
test (pallets/node-authorization)	24s
test (pallets/offences)	24s
test (pallets/runtime-upgrade)	32s
test (pallets/session-benchmarking)	25s
test (pallets/statement)	23s
test (primitives/cord)	25s
test (primitives/identifier)	1s
test (primitives/network-membership)	1s
test (runtimes/common)	1s
test (runtimes/braid)	1s
test (runtimes/loom)	1s
test (runtimes/weave)	1s
test (utilities)	1s
test (test-utils)	1s
	8m 43s

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