explaintest create stats function cannot works

[lysu]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. Minimal reproduce step (Required)

cd cmd/explaintest
./run-tests.sh -c all

2. What did you expect to see? (Required)

update new stats to `s` folder

3. What did you see instead (Required)

./run-tests.sh -c all
extracting statistics: s
building tidb-server binary: ./explaintest_tidb-server
building portgenerator binary: ./portgenerator
building importer binary: ./importer
building explain-test binary: ./explain_test
start tidb-server, log file: ./explain-test.out
tidb-server(PID: 55401) started
create all cases
import data for table dt of test explain_complex_stats:
[2021/03/18 13:45:53.468 +08:00] [ERROR] [main.go:33] ["parse cmd flags"] [error="'2000' is an invalid flag"] [errorVerbose="'2000' is an invalid flag\nmain.(*Config).Parse\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/importer/config.go:133\nmain.main\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/importer/main.go:27\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:225\nruntime.goexit\n\t/usr/local/go/src/runtime/asm_arm64.s:1130"] [stack="main.main\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/importer/main.go:33\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:225"]
[2021/03/18 13:45:53.470 +08:00] [FATAL] [main.go:411] ["importer failed"] [error="exit status 2"] [stack="main.(*tester).create\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/explaintest/main.go:411\nmain.(*tester).execute\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/explaintest/main.go:327\nmain.(*tester).Run\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/explaintest/main.go:158\nmain.main\n\t/Users/robi/Code/go/src/github.com/pingcap/tidb/cmd/explaintest/main.go:697\nruntime.main\n\t/usr/local/go/src/runtime/proc.go:225"]

4. What is your TiDB version? (Required)

3cfb984

[jebter]

The code path has changed. I will close it. Please try the latest version. If there are any updates, you can reopen it.