Update GHA workflow to eliminate some redundant jobs #173

Job	Run time
Setup Build Matrix (false, ion-rust, windows, macos, ubuntu, al2-x86, al2-arm, windows, macos, ub...	1s
Build and Test (windows, default)	2m 52s
Build and Test (windows, all)	3m 5s
Build and Test (windows, experimental-ion-hash)	3m 31s
Build and Test (windows, experimental)	3m 5s
Build and Test (macos, default)	3m 47s
Build and Test (macos, all)	3m 38s
Build and Test (macos, experimental-ion-hash)	3m 55s
Build and Test (macos, experimental)	5m 33s
Build and Test (ubuntu, default)	1m 36s
Build and Test (ubuntu, all)	2m 32s
Build and Test (ubuntu, experimental-ion-hash)	1m 36s
Build and Test (ubuntu, experimental)	1m 34s
Build and Test Confirmation	1s
	36m 46s

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