fix: [M3-9034] - Use empty string instead of unknown for delete dialog titles - #12701

[eslint] reported by reviewdog 🐶 Use of theme.spacing() method is deprecated. Use theme.spacingFunction instead. See: https://linode.github.io/manager/development-guide/16-design-tokens.html#spacing Raw Output: {"ruleId":"@linode/cloud-manager/no-mui-theme-spacing","severity":1,"message":"Use of theme.spacing() method is deprecated. Use theme.spacingFunction instead. See: https://linode.github.io/manager/development-guide/16-design-tokens.html#spacing","line":228,"column":18,"nodeType":"CallExpression","messageId":"themeSpacingMethodUsage","endLine":228,"endColumn":33}