Fix sidekiq transaction check to be decomposition aware

What does this MR do and why?

• Fix sidekiq transaction check to be decomposition aware
• Add missing spec coverage

Related issue: #346697 (closed)

Screenshots or screen recordings

Before vs after

$ GITLAB_USE_MODEL_LOAD_BALANCING=1 bin/rspec spec/initializers/forbid_sidekiq_in_transactions_spec.rb
Run options: include {:focus=>true}

All examples were filtered out; ignoring {:focus=>true}

Test environment set up in 6.325628 seconds
...F

Failures:

  1) Sidekiq::Worker forbids queue sidekiq worker in a Ci::ApplicationRecord transaction
     Failure/Error: expect { worker_class.perform_async }.to raise_error(Sidekiq::Worker::EnqueueFromTransactionError)
       expected Sidekiq::Worker::EnqueueFromTransactionError but nothing was raised
     # ./spec/initializers/forbid_sidekiq_in_transactions_spec.rb:35:in `block (3 levels) in <top (required)>'
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:126:in `block in write_using_load_balancer'
     # ./lib/gitlab/database/load_balancing/load_balancer.rb:112:in `block in read_write'
     # ./lib/gitlab/database/load_balancing/load_balancer.rb:172:in `retry_with_backoff'
     # ./lib/gitlab/database/load_balancing/load_balancer.rb:110:in `read_write'
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:125:in `write_using_load_balancer'
     # ./lib/gitlab/database/load_balancing/connection_proxy.rb:77:in `transaction'
     # ./lib/gitlab/database.rb:261:in `block in transaction'
     # ./lib/gitlab/database.rb:260:in `transaction'
     # ./spec/initializers/forbid_sidekiq_in_transactions_spec.rb:34:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:412:in `block (3 levels) in <top (required)>'
     # ./spec/support/sidekiq_middleware.rb:9:in `with_sidekiq_server_middleware'
     # ./spec/spec_helper.rb:403:in `block (2 levels) in <top (required)>'
     # ./spec/spec_helper.rb:399:in `block (3 levels) in <top (required)>'
     # ./lib/gitlab/application_context.rb:31:in `with_raw_context'
     # ./spec/spec_helper.rb:399:in `block (2 levels) in <top (required)>'
     # ./spec/support/database/query_analyzer.rb:9:in `block (3 levels) in <main>'
     # ./lib/gitlab/database/query_analyzer.rb:42:in `within'
     # ./spec/support/database/query_analyzer.rb:9:in `block (2 levels) in <main>'
     # ./spec/support/database/prevent_cross_joins.rb:102:in `block (3 levels) in <main>'
     # ./spec/support/database/prevent_cross_joins.rb:56:in `with_cross_joins_prevented'
     # ./spec/support/database/prevent_cross_joins.rb:102:in `block (2 levels) in <main>'

Finished in 7.7 seconds (files took 10.21 seconds to load)
4 examples, 1 failure

Failed examples:

rspec ./spec/initializers/forbid_sidekiq_in_transactions_spec.rb:33 # Sidekiq::Worker forbids queue sidekiq worker in a Ci::ApplicationRecord transaction

$ GITLAB_USE_MODEL_LOAD_BALANCING=1 bin/rspec spec/initializers/forbid_sidekiq_in_transactions_spec.rb
Run options: include {:focus=>true}

All examples were filtered out; ignoring {:focus=>true}

Test environment set up in 6.248666 seconds
....

Finished in 7.66 seconds (files took 9.98 seconds to load)
4 examples, 0 failures

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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