Ensure triggers are enabled when operation fails in PostgreSQL

[fatkodima]

Fixes #50191.

Shortened repro script:

$ cd activerecord
$ ARCONN=postgresql bin/test test/cases/fixtures_test.rb test/cases/adapters/postgresql/deferred_constraints_test.rb -n "/^(?:FixturesTest#(?:test_bulk_insert_with_a_multi_statement_query_raises_an_exception_when_any_insert_fails)|PostgresqlDeferredConstraintsTest#(?:test_defer_constraints_with_specific_fk))$/" --seed 49401

When fixture test executes

rails/activerecord/test/cases/fixtures_test.rb

Lines 113 to 129 in 139c567

	def test_bulk_insert_with_a_multi_statement_query_raises_an_exception_when_any_insert_fails
	require "models/aircraft"
	assert_equal false, Aircraft.columns_hash["wheels_count"].null
	fixtures = {
	"aircraft" => [
	{ "name" => "working_aircrafts", "wheels_count" => 2 },
	{ "name" => "broken_aircrafts", "wheels_count" => nil },
	]
	}
	assert_no_difference "Aircraft.count" do
	assert_raises(ActiveRecord::NotNullViolation) do
	ActiveRecord::Base.connection.insert_fixtures_set(fixtures)
	end
	end
	end

insert_fixtire_set from line 126 uses disable_referential_integrity. An error is raised, but triggers are not enabled back in

rails/activerecord/lib/active_record/connection_adapters/postgresql/referential_integrity.rb

Lines 7 to 39 in 139c567

	def disable_referential_integrity # :nodoc:
	original_exception = nil
	begin
	transaction(requires_new: true) do
	execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} DISABLE TRIGGER ALL" }.join(";"))
	end
	rescue ActiveRecord::ActiveRecordError => e
	original_exception = e
	end
	begin
	yield
	rescue ActiveRecord::InvalidForeignKey => e
	warn <<-WARNING
	WARNING: Rails was not able to disable referential integrity.
	This is most likely caused due to missing permissions.
	Rails needs superuser privileges to disable referential integrity.
	cause: #{original_exception&.message}
	WARNING
	raise e
	end
	begin
	transaction(requires_new: true) do
	execute(tables.collect { |name| "ALTER TABLE #{quote_table_name(name)} ENABLE TRIGGER ALL" }.join(";"))
	end
	rescue ActiveRecord::ActiveRecordError
	end
	end

and so for all the other tests from PostgresqlDeferredConstraintsTest they are not enabled and any deferrable foreign keys are just disabled.

cc @yahonda