fix(mysql2): prevent onResult callback from being re-wrapped on every packet

[myeongseoklee]

What does this PR do?

Fixes a bug in mysql2 instrumentation where onResult callback is re-wrapped on every execute() call, causing stack overflow with large prepared statement params.

The Problem:

In bindExecute and wrapExecute, the onResult callback gets wrapped on every packet. MySQL's prepared statement protocol sends one packet per parameter definition. For queries with 3,366+ params, execute() is called 3,369 times, nesting the callback 3,369 layers deep → Stack Overflow.

The Fix:

Add a _ddWrapped flag to prevent re-wrapping callbacks that have already been wrapped.

- if (onResult) {
+ if (onResult && !onResult._ddWrapped) {
    this.onResult = function () {
      return commandFinishCh.runStores(ctx, onResult, this, ...arguments)
    }
+   this.onResult._ddWrapped = true
  }

Motivation

• Fixes [BUG]: mysql2 instrumentation causes stack overflow with large prepared statement params #7074
• Production apps using bulk inserts with 3,300+ params crash with Maximum call stack size exceeded
• Similar pattern to [BUG]: Infinite recursion in aws-sdk instrumentation on dd-trace 5.80.0 #6985 (aws-sdk infinite recursion fix)

Reproduction Repository: https://github.com/myeongseoklee/mysql2-callstack-reproduction

git clone https://github.com/myeongseoklee/mysql2-callstack-reproduction.git
cd mysql2-callstack-reproduction
npm install && npm run docker:up
npm run reproduce      # Before fix: crashes
npm run debug:wrap     # Shows 3,369 execute() calls for 3,366 params

Additional Notes

Evidence:

Params	execute() calls	Before Fix	After Fix
3,060	3,063	✅ OK	✅ OK
3,366	3,369	❌ Crash	✅ OK