[8.14] [Fix] Add missing totalSeconds field (#182093) (#182095)

# Backport

This will backport the following commits from `main` to `8.14`:
- [[Fix] Add missing totalSeconds field
(#182093)](#182093)

<!--- Backport version: 9.4.3 -->

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

<!--BACKPORT [{"author":{"name":"Alex
Szabo","email":"alex.szabo@elastic.co"},"sourceCommit":{"committedDate":"2024-04-30T10:09:02Z","message":"[Fix]
Add missing totalSeconds field (#182093)\n\n## Summary\r\nThe PR
#182001 was verified at a\r\npoint
where typechecking was missing for a bit, this allowed a
missing\r\nfield to slip in. This PR tries to fix
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Add missing totalSeconds
field","number":182093,"url":"#182093
Add missing totalSeconds field (#182093)\n\n## Summary\r\nThe PR
#182001 was verified at a\r\npoint
where typechecking was missing for a bit, this allowed a
missing\r\nfield to slip in. This PR tries to fix
it.","sha":"370a7f5ec625fec1d082b331bfe431b68ed63688"}},"sourceBranch":"main","suggestedTargetBranches":["8.14"],"targetPullRequestStates":[{"branch":"8.14","label":"v8.14.0","branchLabelMappingKey":"^v(\\d+).(\\d+).\\d+$","isSourceBranch":false,"state":"NOT_CREATED"},{"branch":"main","label":"v8.15.0","branchLabelMappingKey":"^v8.15.0$","isSourceBranch":true,"state":"MERGED","url":"#182093
Add missing totalSeconds field (#182093)\n\n## Summary\r\nThe PR
#182001 was verified at a\r\npoint
where typechecking was missing for a bit, this allowed a
missing\r\nfield to slip in. This PR tries to fix
it.","sha":"370a7f5ec625fec1d082b331bfe431b68ed63688"}}]}] BACKPORT-->

Co-authored-by: Alex Szabo <alex.szabo@elastic.co>

x-pack/plugins/observability_solution/profiling/server/routes/apm.ts

@@ -83,6 +83,7 @@ export function registerTopNFunctionsAPMTransactionsRoute({
               indices: transactionIndices.split(','),
               stacktraceIdsField: 'transaction.profiler_stack_trace_ids',
               limit: 1000,
+              totalSeconds: endSecs - startSecs,
             });
             const apmFunction = apmFunctions.TopN.find(
               (topNFunction) => topNFunction.Frame.FunctionName === functionName