[8.6] [Discover] Fix flaky runtime field test (#147006) (#147068)

# Backport

This will backport the following commits from `main` to `8.6`:
- [[Discover] Fix flaky runtime field test
(#147006)](#147006)

<!--- Backport version: 8.9.7 -->

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

<!--BACKPORT [{"author":{"name":"Julia
Rechkunova","email":"[email protected]"},"sourceCommit":{"committedDate":"2022-12-06T08:08:35Z","message":"[Discover]
Fix flaky runtime field test (#147006)\n\nCloses
https://github.com/elastic/kibana/issues/146996\r\n\r\nhttps://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/1630","sha":"0d2c7e54988fcef3b1b7ee98071c0d508ed9b8b9","branchLabelMapping":{"^v8.7.0$":"main","^v(\\d+).(\\d+).\\d+$":"$1.$2"}},"sourcePullRequest":{"labels":["release_note:skip","Team:DataDiscovery","backport:prev-minor","v8.7.0"],"number":147006,"url":"https://github.com/elastic/kibana/pull/147006","mergeCommit":{"message":"[Discover]
Fix flaky runtime field test (#147006)\n\nCloses
https://github.com/elastic/kibana/issues/146996\r\n\r\nhttps://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/1630","sha":"0d2c7e54988fcef3b1b7ee98071c0d508ed9b8b9"}},"sourceBranch":"main","suggestedTargetBranches":[],"targetPullRequestStates":[{"branch":"main","label":"v8.7.0","labelRegex":"^v8.7.0$","isSourceBranch":true,"state":"MERGED","url":"https://github.com/elastic/kibana/pull/147006","number":147006,"mergeCommit":{"message":"[Discover]
Fix flaky runtime field test (#147006)\n\nCloses
https://github.com/elastic/kibana/issues/146996\r\n\r\nhttps://buildkite.com/elastic/kibana-flaky-test-suite-runner/builds/1630","sha":"0d2c7e54988fcef3b1b7ee98071c0d508ed9b8b9"}}]}]
BACKPORT-->

Co-authored-by: Julia Rechkunova <[email protected]>

test/functional/page_objects/discover_page.ts

@@ -377,14 +377,14 @@ export class DiscoverPageObject extends FtrService {
 
   public async editField(field: string) {
     await this.retry.try(async () => {
-      await this.testSubjects.click(`field-${field}`);
+      await this.clickFieldListItem(field);
       await this.testSubjects.click(`discoverFieldListPanelEdit-${field}`);
       await this.find.byClassName('indexPatternFieldEditor__form');
     });
   }
 
   public async removeField(field: string) {
-    await this.testSubjects.click(`field-${field}`);
+    await this.clickFieldListItem(field);
     await this.testSubjects.click(`discoverFieldListPanelDelete-${field}`);
     await this.testSubjects.existOrFail('runtimeFieldDeleteConfirmModal');
     await this.fieldEditor.confirmDelete();