Test compaction filter

[hicqu]

What problem does this PR solve?

Add a test case for gc in compaction filter.

What is changed and how does it work?

Check List

Tests

Code changes

• Has Go code change

Side effects

Related changes

Does this PR introduce a user-facing change?:

No.

NONE

[cosven]

Case 2 fails sometimes

2020/12/25 07:35:13 control.go:348: [info] begin to set up database
2020/12/25 07:35:13 control.go:350: [info] begin to set up database on  127.0.0.1:2379
2020/12/25 07:35:13 control.go:350: [info] begin to set up database on  127.0.0.1:4000
2020/12/25 07:35:13 control.go:350: [info] begin to set up database on  127.0.0.1:20160
2020/12/25 07:35:13 control.go:371: [info] begin to set up client
2020/12/25 07:35:13 control.go:374: [info] begin to set up db client for node  127.0.0.1:4000
2020/12/25 07:35:13 main.go:67: [info] [gc-in-compaction-filter] connnecting to tidb root@tcp(127.0.0.1:4000)/...
[2020/12/25 07:35:13.545 +00:00] [INFO] [client.go:125] ["[pd] create pd client with endpoints"] [pd-address="[127.0.0.1:2379]"]
[2020/12/25 07:35:13.549 +00:00] [INFO] [client.go:227] ["[pd] switch leader"] [new-leader=http://127.0.0.1:2379] [old-leader=]
[2020/12/25 07:35:13.549 +00:00] [INFO] [client.go:144] ["[pd] init cluster id"] [cluster-id=6910086940565119238]
2020/12/25 07:35:13 panic_check.go:34: [warning] plugin panic check won't work
2020/12/25 07:35:13 control.go:298: [info] run client 0...
2020/12/25 07:35:13 cases.go:39: [info] [gc-in-compaction-filter] load safe point 421758520118738944
2020/12/25 07:35:18 cases.go:39: [info] [gc-in-compaction-filter] load safe point 421758520118738944
2020/12/25 07:35:23 cases.go:163: [fatal] [gc-in-compaction-filter] the latest version before safe point is cleaned

Case 1 also fails sometimes