[FIX] base_import: one product imported twice

Steps to reproduce:
1. Install stock
2. Go to Inventory > Products
3. Cog wheel > Import records
4. Make a xlsx document where:
5. the first sheet has at least 2400 records (with header)
6. the second sheet only one record (with header)
7. Upload the document
8. Select the second sheet
9. Set batch limit at 2000
10. Click on import
11. 2 records successfully imported

Cause of the issue:
When initially uploaded, this.state.fileLength
is set to the length of the first sheet
And isn't refreshed when changing sheet

opw-3507544

closes odoo/odoo#139470

X-original-commit: 27f0a0253bc9b44854e5d6436d6e550429cdb93c
Signed-off-by: Luca Vitali (luvi) <luvi@odoo.com>
Signed-off-by: Antoine Demany (ande) <ande@odoo.com>

addons/base_import/static/src/import_action/import_action.js

@@ -103,7 +103,13 @@ export class ImportAction extends Component {
 
     async onOptionChanged(name, value, fieldName = null) {
         this.model.block();
-        await this.model.setOption(name, value, fieldName);
+        const result = await this.model.setOption(name, value, fieldName);
+        if (result) {
+            const { res, error } = result;
+            if (!error && res.file_length) {
+                this.state.fileLength = res.file_length;
+            }
+        }
         this.model.unblock();
     }
 

addons/base_import/static/src/import_model.js

@@ -313,7 +313,7 @@ export class BaseImportModel {
         }
         this.importOptionsValues[optionName].value = value;
         if (this.importOptionsValues[optionName].reloadParse) {
-            await this.updateData();
+            return this.updateData();
         }
     }