Exist queries are retryable

[aidanharan]

Fix following tests:

https://github.com/rails-sqlserver/activerecord-sqlserver-adapter/actions/runs/13201053254/job/36852898476

  4) Failure:
ActiveRecord::AdapterConnectionTest#test_0015_idempotent SELECT queries allow retries [/usr/local/bundle/bundler/gems/rails-cd4708bbcd0d/activerecord/test/cases/adapter_test.rb:716]:
Expected false to be truthy.

Skipped:
ActiveRecord::AdapterConnectionTest#test_0015_idempotent SELECT queries allow retries [/usr/local/bundle/bundler/gems/rails-cd4708bbcd0d/activerecord/test/cases/adapter_test.rb:716]:
kill_connection_from_server unsupported

  5) Failure:
ActiveRecord::AdapterConnectionTest#test_0016_query cacheable idempotent SELECT queries allow retries [/usr/local/bundle/bundler/gems/rails-cd4708bbcd0d/activerecord/test/cases/adapter_test.rb:735]:
EXEC sp_executesql N'SELECT 1 AS one FROM [posts] ORDER BY [posts].[id] ASC OFFSET 0 ROWS FETCH NEXT @0 ROWS ONLY', N'@0 int', @0 = 1 was not retryable

Skipped:
ActiveRecord::AdapterConnectionTest#test_0016_query cacheable idempotent SELECT queries allow retries [/usr/local/bundle/bundler/gems/rails-cd4708bbcd0d/activerecord/test/cases/adapter_test.rb:735]:
kill_connection_from_server unsupported

Ref: rails/rails#54436