Improve handling of -short flag in tests (#9075)

As a small developer quality of life improvement, I found many individual unit tests that take longer than around a second to complete, and set them to skip when run under `go test -short`.

On my machine, the wall timings for tests (with `go test -count=1 ./...` and optionally `-short` and `-race`) are roughly:

- Long tests, no race detector: about 1m42s
- Short tests, no race detector: about 17s
- Long tests, race detector enabled: about 2m1s
- Short tests, race detector enabled: about 28s

This PR is split into many commits each touching a single package, with commit messages detailing the approximate timing change per package.

types/part_set_test.go

@@ -16,6 +16,10 @@ const (
 )
 
 func TestBasicPartSet(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	// Construct random data of size partSize * 100
 	nParts := 100
 	data := tmrand.Bytes(testPartSize * nParts)
@@ -64,6 +68,10 @@ func TestBasicPartSet(t *testing.T) {
 }
 
 func TestWrongProof(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	// Construct random data of size partSize * 100
 	data := tmrand.Bytes(testPartSize * 100)
 	partSet := NewPartSetFromData(data, testPartSize)
@@ -89,6 +97,10 @@ func TestWrongProof(t *testing.T) {
 }
 
 func TestPartSetHeaderValidateBasic(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	testCases := []struct {
 		testName              string
 		malleatePartSetHeader func(*PartSetHeader)
@@ -110,6 +122,10 @@ func TestPartSetHeaderValidateBasic(t *testing.T) {
 }
 
 func TestPartValidateBasic(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	testCases := []struct {
 		testName     string
 		malleatePart func(*Part)

types/validator_set_test.go

@@ -1207,6 +1207,10 @@ func applyChangesToValSet(t *testing.T, expErr error, valSet *ValidatorSet, vals
 }
 
 func TestValSetUpdatePriorityOrderTests(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping test in short mode")
+	}
+
 	const nMaxElections int32 = 5000
 
 	testCases := []testVSetCfg{