[FIX] tools: avoid crashes if expression is too large

When passing a very large expression to `literal_eval`, the odoo server crashes.
To avoid this behavior, a limit needs to be set by using the env varaible `ODOO_LIMIT_LITEVAL_BUFFER`.
If the variable is not set, it defaults to 100Kib.

closes odoo/odoo#121530

Signed-off-by: Vranckx Florian (flvr) <flvr@odoo.com>