Replace use of return keyword as logic control inside AR transactions, as this is not supported in Ruby 3

[duknic]

Fixing the below deprecation warning as we prepare CRMP and associated plugins (i.e. this, draft_approve) for Ruby 3 upgrade.

DEPRECATION WARNING: Using `return`, `break` or `throw` to exit a transaction block is
deprecated without replacement. .... This results
in the transaction being committed, but in the next release of Rails
it will rollback.
 (called from in_new_draft_transaction_helper at /Users/38degrees/.rvm/gems/ruby-2.7.6/bundler/gems/draft_approve-ccf87a589661/lib/draft_approve/transaction.rb:85)

# and

/draft_approve/lib/draft_approve/models/draft_transaction.rb:60

I'll be the first to say this is not a pretty fix.
It tweaks some of the logic used inside Active Record transaction blocks to remove the old syntax and replaces it with variable assignments than then return stuff outside of the block. Thrilling stuff 😆