[8.x] [Lens] Fix filter labels (elastic#211998) (elastic#212287)

# Backport

This will backport the following commits from `main` to `8.x`:
- [[Lens] Fix filter labels
(elastic#211998)](elastic#211998)

<!--- Backport version: 9.6.6 -->

### Questions ?
Please refer to the [Backport tool
documentation](https://github.com/sorenlouv/backport)

<!--BACKPORT [{"author":{"name":"Nick
Partridge","email":"nicholas.partridge@elastic.co"},"sourceCommit":{"committedDate":"2025-02-24T17:02:48Z","message":"[Lens]
Fix filter labels (elastic#211998)\n\nFixes issue causing filter labels to
render as `undefined`. Filter labels now display
correctly.","sha":"4a8928d5d44dc1e6363389bc0bd1f20049fa86ec","branchLabelMapping":{"^v9.1.0$":"main","^v8.19.0$":"8.x","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["bug","Team:Visualizations","release_note:skip","v9.0.0","backport:version","v8.18.0","v9.1.0","v8.19.0"],"title":"[Lens]
Fix filter
labels","number":211998,"url":"https://github.com/elastic/kibana/pull/211998","mergeCommit":{"message":"[Lens]
Fix filter labels (elastic#211998)\n\nFixes issue causing filter labels to
render as `undefined`. Filter labels now display
correctly.","sha":"4a8928d5d44dc1e6363389bc0bd1f20049fa86ec"}},"sourceBranch":"main","suggestedTargetBranches":["9.0","8.18","8.x"],"targetPullRequestStates":[{"branch":"9.0","label":"v9.0.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"8.18","label":"v8.18.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v9.1.0","branchLabelMappingKey":"^v9.1.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/211998","number":211998,"mergeCommit":{"message":"[Lens]
Fix filter labels (elastic#211998)\n\nFixes issue causing filter labels to
render as `undefined`. Filter labels now display
correctly.","sha":"4a8928d5d44dc1e6363389bc0bd1f20049fa86ec"}},{"branch":"8.x","label":"v8.19.0","branchLabelMappingKey":"^v8.19.0$","isSourceBranch":false,"state":"NOT_CREATED"}]}]
BACKPORT-->

Co-authored-by: Nick Partridge <nicholas.partridge@elastic.co>

src/platform/plugins/shared/unified_search/public/filter_badge/filter_content/filter_content.tsx

@@ -51,11 +51,11 @@ export interface FilterContentProps {
 }
 
 export function FilterContent({ filter, valueLabel, fieldLabel, hideAlias }: FilterContentProps) {
-  if (!hideAlias && filter.meta.alias !== null) {
+  if (!hideAlias && filter.meta.alias != null) {
     return (
       <>
         <Prefix prefix={filter.meta.negate} />
-        <FilterValue value={`${filter.meta.alias}`} />
+        <FilterValue value={filter.meta.alias} />
       </>
     );
   }

x-pack/test/functional/apps/lens/group4/dashboard.ts

@@ -77,6 +77,14 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
       await lens.goToTimeRange();
       await retry.try(async () => {
         await clickInChart(30, 5); // hardcoded position of bar, depends heavy on data and charts implementation
+        const filters = await find.allByCssSelector('.euiCheckbox');
+        expect(filters).length(2);
+        const [timeFilter, ipFilter] = filters;
+        expect(await timeFilter.getVisibleText()).to.be(
+          '@timestamp: Sep 21, 2015 @ 09:00:00.000 to Sep 21, 2015 @ 12:00:00.000'
+        );
+        expect(await ipFilter.getVisibleText()).to.be('ip: 97.220.3.248');
+
         await testSubjects.existOrFail('applyFiltersPopoverButton', { timeout: 2500 });
       });