Add gcov-based test pruning with file-level coverage cache #4989

Job	Run time
Detect File Changes	9s
Lint Gate	1m 34s
Rebuild Coverage Cache	25m 34s
Github (ubuntu, mpi, debug, true)	1h 51m 31s
Github (ubuntu, no-mpi, single, no-debug, false)	32m 28s
Github (macos, mpi, debug, false)	54m 34s
Github (ubuntu, mpi, no-debug, true)	1h 34m 58s
Github (ubuntu, mpi, debug, false)	3h 38m 58s
Github (ubuntu, mpi, no-debug, false)	2h 15m 13s
Github (macos, mpi, no-debug, false)	1h 13m 19s
${{ matrix.cluster_name }} (${{ matrix.device }}${{ (((matrix.interface != 'none') && format('-{0}', matrix.interface)) \|\| '') }}${{ (((matrix.shard != '') && format(' [{0}]', matrix.shard)) \|\| '') }})	0s
	12h 28m 18s

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