[serverless] add sorting to Discover CSV tests (#179901)

## Summary

Add sorting via api calls.
Update mappings file to load field data.
Update snapshots

x-pack/test/functional/es_archives/reporting/unmapped_fields/mappings.json

@@ -6,7 +6,8 @@
       "dynamic": false,
       "properties": {
         "text": {
-          "type": "text"
+          "type": "text",
+          "fielddata": "true"
         }
       }
     }

x-pack/test_serverless/api_integration/test_suites/common/reporting/generate_csv_discover.ts

@@ -184,6 +184,7 @@ export default ({ getService }: FtrProviderContext) => {
               query: { language: 'kuery', query: '' },
               fields: fields.map((field) => ({ field, include_unmapped: 'true' })),
               filter: [],
+              sort: [{ text: 'asc' as SortDirection }],
             },
             title: 'Untitled discover search',
             version: '8.14.0',
@@ -195,19 +196,19 @@ export default ({ getService }: FtrProviderContext) => {
 
       it('includes an unmapped field to the report', async () => {
         const csvFile = await generateCsvReportWithUnmapped(['text', 'unmapped']);
-        expect((csvFile as string).length).to.be(88);
+        expect((csvFile as string).length).to.be(92);
         expectSnapshot(createPartialCsv(csvFile)).toMatch();
       });
 
       it('includes an unmapped nested field to the report', async () => {
         const csvFile = await generateCsvReportWithUnmapped(['text', 'nested.unmapped']);
-        expect((csvFile as string).length).to.be(97);
+        expect((csvFile as string).length).to.be(101);
         expectSnapshot(createPartialCsv(csvFile)).toMatch();
       });
 
       it('includes all unmapped fields to the report', async () => {
         const csvFile = await generateCsvReportWithUnmapped(['*']);
-        expect((csvFile as string).length).to.be(120);
+        expect((csvFile as string).length).to.be(124);
         expectSnapshot(createPartialCsv(csvFile)).toMatch();
       });
     });