chore: ignore MySQL client sent SELECT $$

[tisonkun]

I hereby agree to the terms of the GreptimeDB CLA

What's changed and what's your intention?

This closes #2514.

Checklist

• I have written the necessary rustdoc comments.
• I have added the necessary unit tests and integration tests.

Refer to a related PR or issue link (optional)

[codecov]

Codecov Report

Merging #2896 (f7b0b07) into develop (5a99f09) will decrease coverage by 0.60%.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #2896      +/-   ##
===========================================
- Coverage    85.06%   84.47%   -0.60%     
===========================================
  Files          753      753              
  Lines       119059   119062       +3     
===========================================
- Hits        101281   100576     -705     
- Misses       17778    18486     +708     

[WenyXu]

Thank @tisonkun, Almost LGTM. Maybe it's better to add a simple sqlness for this case, If you don't mind ❤️

[tisonkun]

@WenyXu Thanks for your review! This patch is active for MySQL interface only. I try sqlness case locally but it doesn't seem go through the MySQL server logic.

Is there other proper place to write IT cases?

[WenyXu]

@WenyXu Thanks for your review! This patch is active for MySQL interface only. I try sqlness case locally but it doesn't seem go through the MySQL server logic.

Is there other proper place to write IT cases?

Oh, My bad. You reminded me that our sqlness is using the gRPC protocol. Let's go ahead and leave this IT case as future work.

[QuenKar]

LGTM