[bug] Icon color doesn't update with the color theme

<img width="443" alt="Image" src="https://github.com/user-attachments/assets/c0f1d612-a6f1-4a00-8f0a-cdeae1787738" />

All icons should use our color tokens so they are automatically updated with the theme. In this case, it should be "content-secondary".

cc @BrunoQuaresma as it relates to https://github.com/coder/coder/issues/15613?issue=coder%7Ccoder%7C14780