Fix: Database query on opportunity table (#20017)

## Automated fix for [bug
30463](https://sonarly.com/issue/30463?type=bug)

**Severity:** `critical`

### Summary
When createMany is called with upsert:true and records lack pre-assigned
IDs, findExistingRecords() executes a SELECT with no WHERE clause,
scanning the entire table. This caused an 11-second transaction on the
opportunity table (2.9s query + 7.7s JS processing).

### Root Cause
1. WHY was the transaction 11 seconds? Because a SELECT on the
opportunity table took 2.9s and its result processing took 7.7s.
2. WHY did the SELECT take 2.9s? Because it was a full table scan with
NO WHERE clause, fetching every record (including soft-deleted).
3. WHY was there no WHERE clause? Because findExistingRecords() in
common-create-many-query-runner.service.ts calls buildWhereConditions()
which returned an empty array, so no .orWhere() was applied to the query
builder before .getMany() was called.
4. WHY did buildWhereConditions return empty? Because the input records
had no pre-assigned IDs and the opportunity object has no other unique
fields, so there were no conflicting field values to build conditions
from.
5. WHY wasn't the empty-conditions case guarded? The
findExistingRecords() method was written without an early-return check
for empty whereConditions — it always executes the query regardless.

**Introduced by:** etiennejouan on 2025-10-15 in commit
[`4ae2999`](4ae2999)
> Common Api - createOne/Many (#15083)

### Suggested Fix
Added an early return in findExistingRecords() when
buildWhereConditions() returns an empty array. When no WHERE conditions
exist (because input records lack values for any unique/conflicting
field), the method now returns an empty array immediately instead of
executing a SELECT with no WHERE clause that scans the entire table.
This prevents the O(n) full table scan + O(n) JS result processing that
caused the 11-second transaction. The downstream categorizeRecords()
correctly handles empty existingRecords by classifying all input records
as recordsToInsert.

---
*Generated by [Sonarly](https://sonarly.com)*

Co-authored-by: Sonarly Claude Code <claude-code@sonarly.com>

Author: sonarly[bot]

packages/twenty-server/src/engine/api/common/common-query-runners/common-create-many-query-runner/common-create-many-query-runner.service.ts

@@ -307,6 +307,10 @@ export class CommonCreateManyQueryRunnerService extends CommonBaseQueryRunnerSer
 
     const whereConditions = buildWhereConditions(args.data, conflictingFields);
 
+    if (whereConditions.length === 0) {
+      return [];
+    }
+
     whereConditions.forEach((condition) => {
       queryBuilder.orWhere(condition);
     });