LabelFilters: Remove redundant css styling (#56653)

* LabelFilters: Remove redundant css

* Remove unused import

public/app/plugins/datasource/prometheus/querybuilder/shared/LabelFilterItem.tsx

@@ -1,4 +1,3 @@
-import { css } from '@emotion/css';
 import { uniqBy } from 'lodash';
 import React, { useState } from 'react';
 
@@ -58,16 +57,6 @@ export function LabelFilterItem({
     return uniqBy([...selectedOptions, ...labelValues], 'value');
   };
 
-  /**
-   * !important here is necessary to show invalid border on all 4 sides of select.
-   * Without it, the invalid state is only visible on 3 sides as the right side is overridden in InputGroup.
-   */
-  const invalidClassNameOverride = invalidLabel
-    ? css`
-        margin-left: 0 !important;
-      `
-    : '';
-
   return (
     <div data-testid="prometheus-dimensions-filter-item">
       <InputGroup>
@@ -107,7 +96,6 @@ export function LabelFilterItem({
               onChange({ ...item, op: change.value } as any as QueryBuilderLabelFilter);
             }
           }}
-          className={invalidClassNameOverride}
         />
 
         <Select