spp_programs: retire the DOM workaround for the form "New" button now that #582 keeps canCreate #589

spp_programs/static/src/js/form_controller_create.js hides .o_form_button_create with style.display = "none",
re-applied on onMounted/onPatched, two timers and a MutationObserver, whenever context.create === false,
this.canCreate === false, or the model is in MODELS_WITHOUT_CREATE. Its comment blames Odoo 19 ("t-if="canCreate"
on the form template does not always prevent the 'New' button from rendering"). The real cause was the
spp_base_common template extension dropping canCreate (#582, fixed in PR #588). With that fix:

• the context.create === false and canCreate === false branches are dead: Odoo never renders the button in those
  cases, so the observer and timers find nothing;
• MODELS_WITHOUT_CREATE (spp.entitlement, spp.entitlement.inkind, spp.program.membership,
  spp.cycle.membership) can be expressed the way spp_programs already does for spp.program
  (create_program.js): this.hideFormCreateButton = true in the FormController patch. Note that all four of
  those forms also carry create="0" on their arch (entitlement_view.xml, entitlement_cash_view.xml,
  program_membership_view.xml, cycle_membership_view.xml), so the list may be redundant altogether; keep the
  flag only if a form of those models exists without the arch attribute.

Also, two comments elsewhere describe the same symptom as an Odoo 19 defect and should be corrected (code is fine):

• spp_drims/static/src/js/hide_dispatch_form_create.js: "Action context 'create': False is unreliable in Odoo 19
  too" — it was unreliable because of the spp_base_common override.
• spp_farmer_registry/static/src/js/registry_restriction.js: the .o_form_button_create entry in its DOM-hiding
  selector list is redundant once this.canCreate = false (which it already sets in onWillStart) is honoured by the
  template. The other selectors (save/cancel/statusbar) and the o_form_readonly class handling are unrelated and stay.

Scope: spp_programs patch bump + HISTORY (and whichever of the other two modules gets a code, not comment, change).
Regression coverage already exists in spp_base_common (test_form_create_button_template.py) and in the e2e suite
(spec 01, test 20).

Refs #582.