plugin:modify conn_ip_example's method parameters and return values

[sourcelliu]

What problem does this PR solve?

I recently researched TiDB's plugin mechanism, using the example provided by the official website (conn_id_example) to compile and generate plugins, but in the process of generating plugins, the following error message appears:

cannot use OnGeneralEvent (type func(context.Context, *variable.SessionVars, "github.com/pingcap/tidb/plugin".GeneralEvent, byte, string) error) as type func(context.Context, *variable.SessionVars, "github.com/pingcap/tidb/plugin".GeneralEvent, string) in field value

What is changed and how it works?

I checked and found that the OnGeneralEvent method in conn_id_example.go is different from the OnGeneralEvent method parameter and return value in plugin/audit.go. Therefore, this pull request modifies the conn_id_example.go method parameter and return value, so that it can be normal. Generate plugin: conn_ip_example-1.so.

Check List

Tests

• Integration test

Code changes
no

Side effects
no

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

Merging #10288 into master will increase coverage by 0.0091%.
The diff coverage is 0%.

@@               Coverage Diff                @@
##             master     #10288        +/-   ##
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+ Coverage   77.6625%   77.6716%   +0.0091%     
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  Files           411        411                
  Lines         85444      85452         +8     
================================================
+ Hits          66358      66372        +14     
+ Misses        14122      14120         -2     
+ Partials       4964       4960         -4

[shenli]

@mantuliu Thanks! Please sign the CLA.
@lysu PTAL

[sourcelliu]

@shenli done.Thanks!

[lysu]

LGTM

[lysu]

/run-all-tests

[jackysp]

LGTM