[TMCU-995] Withdraw fail toast uses incorrect AvatarIcon background color

### Description\n\nMirrors Jira [TMCU-995](https://consensyssoftware.atlassian.net/browse/TMCU-995).\n\nPart of epic #1271 / [TMCU-622](https://consensyssoftware.atlassian.net/browse/TMCU-622).\n\n**Jira status:** To Do\n\n### Jira details\n\n### Impact\n\nThe withdraw fail toast uses an incorrect background color, which causes a visual clash (red icon on blue avatar) when pure black theme is enabled.\n\n### Expected behaviour\n\nThe background color in the withdraw fail toast should be consistent with the theme and not clash with the icon color.\n\n### Actual behaviour\n\nThe toast shows a red icon on a blue avatar background, which clashes visually.\n\n### Steps to reproduce\n\n1. Go to the perps home page.\n2. Select **Withdraw**.\n3. Trigger a withdrawal failure (exact steps to trigger the error are uncertain, but the resulting toast displays the issue).\n\n### Environment\n\nPure black theme enabled.\n\n### Workarounds\n\nNone reported.\n\n_Work item created in Slack from a_ [_message_](https://consensys.slack.com/archives/D05SUTYLX43/p1783033032091679)_._\n