[19.0][MIG] base_user_role_activity: Migration to 19.0 - #8

@copilot use /odoo-migration agent to continue migration. Make sure you can load the needed skills:
odoo-migrate-module: https://github.com/c4a8-odoo/.github/blob/main/skills/odoo-migrate-module/SKILL.md
odoo-tests: https://github.com/c4a8-odoo/.github/blob/main/skills/odoo-tests/SKILL.md

The odoo-migration agent should not push the changes. This should be done by the calling copilot agent.

@copilot use /odoo-migration agent to continue migration. Make sure you can load the needed skills:
odoo-migrate-module: https://github.com/c4a8-odoo/.github/blob/main/skills/odoo-migrate-module/SKI...

Implemented with the /odoo-migration workflow and kept push/commit in the calling agent only. In commit 8f80c35, I removed the invalid keep_done field from base_user_role_activity/data/mail_activity_type.xml, which addresses the Odoo 19 CI failure (Invalid field 'keep_done' in 'mail.activity.type').

@CRogos ich squashe den Commit nach deinem Review.

Kannst gerne squashen.