Before this commit, we check if the bill_type in the project is equal
to 'customer_type' but this field can only be either 'customer_task' or
'customer_project'. Thus, this condition will always be False.
This commit changes the condition to check if the bill_type is equal to
'customer_project'. Then, this condition can be True if the project has
a SOL and his bill_type field is equal to 'customer_project'.
closesodoo/odoo#64012
X-original-commit: d8f7d7369f060f444bcebc0118cc5a2a650f6361
Related: odoo/enterprise#15540
Signed-off-by: Yannick Tivisse (yti) <yti@odoo.com>