Remove has_primary_key?

[yahonda]

Summary

Remove OracleEnhancedAdapter#has_primary_key? entirely. The method was an oracle-enhanced override of an abstract-adapter method that Rails itself removed in commit d1521719c5 ("Removed support for accessing attributes on a has_and_belongs_to_many join table", 2011-01-16) when the HABTM attribute-access path that needed it was retired. oracle-enhanced kept the override, but it has been dead surface for 14+ years.

Why now / why outright removal

• Zero in-tree callers. The only previous user, the original prefetch_primary_key? cache-fill path, was refactored into prefetch_primary_key_from_dictionary and now goes through primary_keys(table_name) directly.
• Not in the Rails abstract API. Current Rails callers use primary_key(table_name) / primary_keys(table_name) instead.
• # :nodoc: — no API contract is being broken.
• The body had also already lost its (owner, desc_table_name) arguments (carried over from pk_and_sequence_for's historical signature, never functional because pk_and_sequence_for itself unconditionally re-resolves them via resolve_data_source_name). The only thing left would have been a one-line wrapper around primary_keys(table_name).any? — not worth keeping.
• The single spec assertion added in Add composite primary key support #2693 (expect(@conn.has_primary_key?("uber_barcodes")).to be true) duplicated the immediately preceding primary_keys assertion; removed alongside the method.

Diff

- def has_primary_key?(table_name, owner = nil, desc_table_name = nil) # :nodoc:
-   primary_keys(table_name).any?
- end
-
  def primary_keys(table_name) # :nodoc:

(Plus the deletion of one redundant spec line.)

Test plan

• bundle exec rspec — full suite, 803 examples, 0 failures, 12 pre-existing pending
• bundle exec rubocop — clean
• No remaining references to has_primary_key? in lib/ or spec/