Clean up temp files more thoroughly after testing. (#7815)

Our test cases spew a lot of files and directories around $TMPDIR.  Make more
thorough use of the testing package's TempDir methods to ensure these are
cleaned up.

In a few cases, this required plumbing test contexts through existing helper
code. In a couple places an explicit path was required, to work around cases
where we do global setup during a TestMain function. Those cases probably
deserve more thorough cleansing (preferably with fire), but for now I have just
worked around it to keep focused on the cleanup.

rpc/test/helpers.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"testing"
 	"time"
 
 	abciclient "github.com/tendermint/tendermint/abci/client"
@@ -57,8 +58,8 @@ func makeAddrs() (p2pAddr, rpcAddr string) {
 	return fmt.Sprintf(addrTemplate, randPort()), fmt.Sprintf(addrTemplate, randPort())
 }
 
-func CreateConfig(testName string) (*config.Config, error) {
-	c, err := config.ResetTestRoot(testName)
+func CreateConfig(t *testing.T, testName string) (*config.Config, error) {
+	c, err := config.ResetTestRoot(t.TempDir(), testName)
 	if err != nil {
 		return nil, err
 	}