[MM-54457] Suggestion list UI discrepancy from Add <user> to a Channel modal (#25340)

* Adjust inputRect dimensions to make suggestion list above/below

Now, the suggestion list will not be placed directly on the input and both
can be seen at once

* Remove position arguments to make suggestion-list correct

When choosing bottom, now the position not overwritten and thus the position will be correct.

Earlier adjustments has been reverted after feedback

* revert adjustments which was faulty

With the new way of configuring the suggestion list, we no longer need to
change the top and bottom

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Co-authored-by: Mattermost Build <build@mattermost.com>

webapp/channels/src/components/suggestion/modal_suggestion_list.tsx

@@ -200,8 +200,6 @@ export default class ModalSuggestionList extends React.PureComponent<Props, Stat
         let position = {};
         if (this.state.position === 'top') {
             position = {bottom: this.state.modalBounds.bottom - this.state.inputBounds.top};
-        } else {
-            position = {top: this.state.inputBounds.bottom - this.state.modalBounds.top};
         }
 
         return (