Add Feedback gutter button width grows with line-number digits

### Description

The inline **Add Feedback** gutter button becomes unusually wide in files with large line counts. Its width appears to track the maximum number of line-number digits in the file.

This reproduces in the current Insiders build and latest Stable. In the reported example, the changed file has about 15,889 lines, and the button stretches across the enlarged line-number gutter.

This looks distinct from #327107: that issue shows a different malformed layout, while this report is specifically about the button width scaling with the line-number gutter.

### Expected

The Add Feedback affordance remains compact regardless of the number of digits in the file line count.

### Actual

The affordance becomes progressively wider as the line-number gutter grows.