[19.0][FIX] hr: cleanup obsolete hr.employee fields + apriori-renamed views

[dnplkndll]

Migration work on the ledoent/OpenUpgrade fork (internal review). Rebased onto current 19.0.

After the hr_contract → hr apriori merge, two classes of stale records
linger and trip cross-cutting view validation later in the migration:

1. ir_model_fields rows + orphan ir_ui_view records for fields the 18.0
   hr_contract module added to hr.employee that no longer exist in 19.0:
   contract_id, contract_ids, contract_warning, first_contract_date,
   vehicle (listed DEL in upgrade_analysis_work.txt as "# NOTHING TO DO"),
   plus contract_template_id, contract_type_id, contract_wage,
   contracts_count, is_in_contract (not flagged by the analyzer but
   verified stale via grep against all 19.0 hr* modules).

2. ir_ui_view records whose xml_ids were auto-renamed by openupgradelib
   (<orig_name>_openupgrade_<id>) during the merge to avoid xml_id
   collision. Two such views exist after the merge:
   res_config_settings_view_form_openupgrade_65293 and
   hr_departure_wizard_view_form_openupgrade_65294. Their arch_db still
   references 18.0-only xpath targets (e.g. //block[@name='employee_rights_setting_container'])
   and parents that 19.0 doesn't ship.

Both classes manifest as a migration crash when l10n_ae's
account_tax_report_data.xml triggers global view validation around
module 217/608 — without this patch the migration fails with either
"Field 'first_contract_date' does not exist in model 'hr.employee'"
or "Element '' cannot be located in parent view".

Add two helpers in pre-migration:

• cleanup_obsolete_hr_employee_fields(env)
• cleanup_openupgrade_renamed_hr_views(env)

Update upgrade_analysis_work.txt: the "# NOTHING TO DO" block for the
DEL fields becomes "# DONE: stale ir_model_fields rows + orphan
ir_ui_view records cleaned up in pre-migration".

[dnplkndll]

Folded into #47 (19.0-fix-hr-null-write-date): both fixes edit hr/19.0.1.1/pre-migration.py at the same anchors, so gitaggregate could not auto-merge them separately. Combined into one branch with both fill_hr_employee_audit_dates + cleanup_obsolete_hr_employee_fields/cleanup_openupgrade_renamed_hr_views as two commits. Removed from repos.yaml.