chore: use -coverpkg for extended code coverage reports #1765

Job	Run time
build (1.20.x, GOARCH=amd64 GOOS=linux, gno)	42s
test (1.20.x, _test.cmd)	2m 16s
build (1.20.x, GOARCH=wasm GOOS=js, gno)	38s
build (1.21.x, GOARCH=amd64 GOOS=linux, gno)	52s
test (1.20.x, _test.pkg)	1m 9s
build (1.21.x, GOARCH=wasm GOOS=js, gno)	37s
test (1.20.x, _test.gnolang.native)	1m 13s
test (1.20.x, _test.gnolang.stdlibs)	2m 5s
test (1.20.x, _test.gnolang.realm)	1m 1s
test (1.20.x, _test.gnolang.pkg0)	7m 43s
test (1.20.x, _test.gnolang.pkg1)	15m 12s
test (1.20.x, _test.gnolang.pkg2)	15m 15s
test (1.20.x, _test.gnolang.other)	1m 4s
test (1.21.x, _test.cmd)	1m 34s
test (1.21.x, _test.pkg)	1m 8s
test (1.21.x, _test.gnolang.native)	1m 36s
test (1.21.x, _test.gnolang.stdlibs)	1m 57s
test (1.21.x, _test.gnolang.realm)	58s
test (1.21.x, _test.gnolang.pkg0)	7m 47s
test (1.21.x, _test.gnolang.pkg1)	15m 11s
test (1.21.x, _test.gnolang.pkg2)	15m 16s
test (1.21.x, _test.gnolang.other)	46s
upload-coverage	0s
	1h 36m 0s

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