Remove patch for AR::Relation#primary_key in Rails 8.0+

[kymmt90]

Problem

Only AR::Relation's primary_key is overridden with bitemporal_id_key.

activerecord-bitemporal/lib/activerecord-bitemporal/bitemporal.rb

Lines 171 to 173 in 35410b4

	def primary_key
	bitemporal_id_key
	end

Therefore, when model.primary_key is called in Rails 8.0+'s finder methods, it returns the original primary_key value instead of bitemporal_id_key. Additionally, this override can cause various other confusions.

Changes

This PR removes the override of AR::Relation#primary_key in Rails 8.0+. The order of AR objects fetched by finder methods is kept as before thanks to #237.

By removing the override of primary_key, AR::Calculations#ids now returns an array of swapped_id instead of bitemporal_id. This is because AR::Relation::Calculations#ids calls primary_key on self.

https://github.com/rails/rails/blob/v8.0.4/activerecord/lib/active_record/relation/calculations.rb#L371

This PR redefines #ids to keep the previous behavior.

[krororo]

LGTM 👍

[kymmt90]

@osyo-manga Thank you for the reviews. Fixed: https://github.com/kufu/activerecord-bitemporal/compare/3b25dcf2127fa41dc7f22f485e0ffc1bf632d99b..ae42c1be33b498741157f09ca8829b3d347ef1e4

[kymmt90]

Reworked on #243.