Touch up settings: alignment, spacing, error states

Fixes https://github.com/vector-im/riot-web/issues/10554

Issues fixed:
* Fields were not ~30px from the avatar (too much right margin)
* Tooltips overflowed the dialog on some resolutions
* SetIdServer didn't have an error state for making the field red
* Spacing between sections in Discovery was wrong (fixed by just removing the problematic n+2 selector - it didn't help anything)

src/components/views/settings/SetIntegrationManager.js

@@ -196,6 +196,7 @@ export default class SetIntegrationManager extends React.Component {
                     autoComplete="off"
                     onChange={this._onUrlChanged}
                     tooltipContent={this._getTooltip()}
+                    tooltipClassName="mx_SetIntegrationManager_tooltip"
                     disabled={this.state.busy}
                     flagInvalid={!!this.state.error}
                 />