[Filters] Fix operator overflowing out popover (#50030) (#50536)

* Fixes combo overflow when the selected field is large

* Prettier quotes

* Changes the style class attribute to use Eui calculation and also the
class name to conform to the BEM naming convention

* Lints src/plugins/newsfeed/public/lib/api.test.ts

src/legacy/core_plugins/data/public/filter/filter_bar/_index.scss

@@ -1,3 +1,4 @@
 @import 'variables';
 @import 'global_filter_group';
 @import 'global_filter_item';
+@import 'filter_editor/index';

src/legacy/core_plugins/data/public/filter/filter_bar/filter_editor/_filter_editor.scss

@@ -0,0 +1,3 @@
+.globalFilterEditor__fieldInput {
+  max-width: $euiSize * 13;
+}

src/legacy/core_plugins/data/public/filter/filter_bar/filter_editor/_index.scss

@@ -0,0 +1 @@
+@import 'filter_editor';

src/legacy/core_plugins/data/public/filter/filter_bar/filter_editor/index.tsx

@@ -245,6 +245,7 @@ class FilterEditorUI extends Component<Props, State> {
   private renderFieldInput() {
     const { selectedIndexPattern, selectedField } = this.state;
     const fields = selectedIndexPattern ? getFilterableFields(selectedIndexPattern) : [];
+
     return (
       <EuiFormRow
         label={this.props.intl.formatMessage({
@@ -265,6 +266,7 @@ class FilterEditorUI extends Component<Props, State> {
           onChange={this.onFieldChange}
           singleSelection={{ asPlainText: true }}
           isClearable={false}
+          className="globalFilterEditor__fieldInput"
           data-test-subj="filterFieldSuggestionList"
         />
       </EuiFormRow>