tiup cluster reload success when tidb.toml contain unknow configuration

[Win-Man]

Bug Report

Please answer these questions before submitting your issue. Thanks!

1. What did you do?

• tiup cluster edit-config sg-devt

server_configs:
  tidb:
    log.slow-threshold: 300
    txn-total-size-limit: 10485760000

• tiup cluster reload sg-devt -R tidb

$ tiup cluster reload sg-devt -R tidb
Starting component `cluster`: /Users/shengang/.tiup/components/cluster/v1.3.2/tiup-cluster reload sg-devt -R tidb
+ [ Serial ] - SSHKeySet: privateKey=/Users/shengang/.tiup/storage/cluster/clusters/sg-devt/ssh/id_rsa, publicKey=/Users/shengang/.tiup/storage/cluster/clusters/sg-devt/ssh/id_rsa.pub
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [Parallel] - UserSSH: user=tidb, host=172.16.5.215
+ [ Serial ] - UpdateTopology: cluster=sg-devt
+ Refresh instance configs
  - Regenerate config pd -> 172.16.5.215:12384 ... Done
  - Regenerate config tikv -> 172.16.5.215:30165 ... Done
  - Regenerate config tidb -> 172.16.5.215:14005 ... Done
  - Regenerate config tiflash -> 172.16.5.215:19005 ... Done
  - Regenerate config cdc -> 172.16.5.215:18305 ... Done
  - Regenerate config prometheus -> 172.16.5.215:19095 ... Done
  - Regenerate config grafana -> 172.16.5.215:13005 ... Done
+ Refresh monitor configs
  - Refresh config node_exporter -> 172.16.5.215 ... Done
  - Refresh config blackbox_exporter -> 172.16.5.215 ... Done
+ [ Serial ] - UpgradeCluster
Restarting component tidb
	Restarting instance 172.16.5.215
	Restart 172.16.5.215 success
Reloaded cluster `sg-devt` successfully

• tiup audit log

2021-03-02T20:08:31.373+0800    ERROR   SSHCommand      {"host": "172.16.5.215", "port": "22", "cmd": "export LANG=C; PATH=$PATH:/usr/bin:/usr/sbin /home/tidb/gangshen/dev/deploy/tidb-14005/bin/tidb-server --help", "error": "Process exited with status 2", "stdout": "", "stderr": "Usage of /home/tidb/gangshen/dev/deploy/tidb-14005/bin/tidb-server:\n  -L string\n    \tlog level: info, debug, warn, error, fatal (default \"info\")\n  -P string\n    \ttidb server port (default \"4000\")\n  -V\tprint version information and exit (default false)\n  -advertise-address string\n    \ttidb server advertise IP\n  -affinity-cpus string\n    \taffinity cpu (cpu-no. separated by comma, e.g. 1,2,3)\n  -config string\n    \tconfig file path\n  -config-check\n    \tcheck config file validity and exit (default false)\n  -config-strict\n    \tenforce config file validity (default false)\n  -cors string\n    \ttidb server allow cors origin\n  -enable-binlog\n    \tenable generate binlog (default false)\n  -host string\n    \ttidb server host (default \"0.0.0.0\")\n  -lease string\n    \tschema lease duration, very dangerous to change only if you know what you do (default \"45s\")\n  -log-file string\n    \tlog file path\n  -log-slow-query string\n    \tslow query file path\n  -metrics-addr string\n    \tprometheus pushgateway address, leaves it empty will disable prometheus push.\n  -metrics-interval uint\n    \tprometheus client push interval in second, set \"0\" to disable prometheus push. (default 15)\n  -path string\n    \ttidb storage path (default \"/tmp/tidb\")\n  -plugin-dir string\n    \tthe folder that hold plugin (default \"/data/deploy/plugin\")\n  -plugin-load string\n    \twait load plugin name(separated by comma)\n  -proxy-protocol-header-timeout uint\n    \tproxy protocol header read timeout, unit is second. (default 5)\n  -proxy-protocol-networks string\n    \tproxy protocol networks allowed IP or *, empty mean disable proxy protocol support\n  -repair-list string\n    \tadmin repair table list\n  -repair-mode\n    \tenable admin repair mode (default false)\n  -report-status\n    \tIf enable status report HTTP service. (default true)\n  -require-secure-transport\n    \trequire client use secure transport\n  -run-ddl\n    \trun ddl worker on this tidb-server (default true)\n  -socket string\n    \tThe socket file to use for connection.\n  -status string\n    \ttidb server status port (default \"10080\")\n  -status-host string\n    \ttidb server status host (default \"0.0.0.0\")\n  -store string\n    \tregistered store name, [tikv, mocktikv] (default \"mocktikv\")\n  -token-limit int\n    \tthe limit of concurrent executed sessions (default 1000)\n"}

2. What did you expect to see?

tiup cluster reload failed.

3. What did you see instead?

tiup cluster reload successfully.

4. What version of TiUP are you using (tiup --version)?

$ tiup --version
v1.3.2 tiup
Go Version: go1.13
Git Branch: release-1.3
GitHash: 2d88460