Fix Members::BaseService to work properly with transactions

What does this MR do?

Fix Members::BaseService to work properly with transactions

We shouldn't schedule Sidekiq jobs directly during service
execution. Instead we should postpone it to after_commit
block where possible.

This will allow running Members services in a transaction without getting Sidekiq::Worker::EnqueueFromTransactionError. E.g.:

ActiveRecord::Base.transaction do
  Members::DestroyService.new(User.last).execute(Member.last)
end

What are the relevant issue numbers?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated via this MR
• Documentation reviewed by technical writer or follow-up review issue created
• Tests added for this feature/bug
• Tested in all supported browsers
• Conforms to the code review guidelines
• Conforms to the merge request performance guidelines
• Conforms to the style guides
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• Link to e2e tests MR added if this MR has Requires e2e tests label. See the Test Planning Process.
• Security reports checked/validated by reviewer