[FIX] account_journal_general_sequence: bottleneck at install

On databases with big amounts of account moves, installation would freeze Odoo for some minutes.

We skip now entry number computation at install, to avoid such cases.

@moduon MT-676

account_journal_general_sequence/__manifest__.py

@@ -9,6 +9,7 @@
     "author": "Moduon, Odoo Community Association (OCA)",
     "license": "LGPL-3",
     "external_dependencies": {"python": ["freezegun"]},
+    "maintainers": ["yajo"],
     "depends": [
         "account",
     ],