fix: transaction state on rollback (#364)

[BuonOmo]

Fixes #258

See #368

[rafiss]

I'm not quite sure why this error happened in the v23.2 test:

 /home/runner/work/activerecord-cockroachdb-adapter/activerecord-cockroachdb-adapter/vendor/bundle/ruby/3.5.0+0/bundler/gems/rails-f926c7902969/activerecord/lib/active_record/connection_adapters/postgresql/database_statements.rb:55:in 'PG::Connection#exec': PG::FeatureNotSupported: ERROR:  at or near "before_insert_trigger": syntax error: unimplemented: this syntax (ActiveRecord::StatementInvalid)
DETAIL:  source SQL:
CREATE TRIGGER before_insert_trigger

v23.2 does not support triggers, but I'm surprised the test tried using one on that version.

[BuonOmo]

@rafiss yeah I didn't cherry pick everything on that one, I believe I should as well. I wanted to first focus on the 7-2 :)