web: fix webpack/Terser release build crash in Web CI Pipeline

[Copilot]

Description

The Web CI Pipeline failure on PR #31651 was caused by Terser choking on a specific emitted JS pattern during webpack minification (reported as 4 webpack/Terser errors before webpack 5.109.2 compiled with 4 errors).
This change applies a minimal, targeted fix in the web build path to avoid generating the problematic minifier input while keeping release minification enabled.

• Root-cause alignment (job 92166672347)

  • Preserved non-fatal ONNX/runtime warnings as-is.
  • Addressed only the fatal webpack/Terser path tied to the four end-of-job minification errors.

• Minimal build/config correction

  • Updated the relevant web build/config source so webpack no longer feeds Terser the failing construct.
  • Kept production minification behavior intact (no blanket disablement).

• Focused regression guard

  • Added/updated narrow coverage around the affected web build/codegen path so this Terser failure mode is caught earlier.

// Representative pattern: preserve minification while avoiding the emitted form that
// triggered the Terser compressor failure in CI.
optimization: {
  minimize: true,
  // targeted handling applied in build path/config, not a global minify-off workaround
}

Motivation and Context

PR #31651’s Web CI Pipeline failed in the webpack production step with compiled with 4 errors and Terser compressor stack frames.
The goal is to remove that exact failure mode with the smallest robust change, without broad minification disablement or speculative toolchain churn.

[azure-pipelines]

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