Add transaction op default

[krystofwoldrich]

📢 Type of change

• Bugfix
• New feature
• Enhancement
• Refactoring

📜 Description

transaction.op is required on Android.

💡 Motivation and Context

closes: #2682

💚 How did you test it?

tests and sample app

📝 Checklist

• I reviewed submitted code
• I added tests to verify changes
• All tests passing
• No breaking changes

🔮 Next steps

• Refactor startTransaction patch #2693

[marandaneto]

Let's double check if startIdleTransaction has to be patched as well, if its an internal and not documented API, we dont need to do that since we always have an op.

[krystofwoldrich]

@marandaneto Checked. startIdleTransaction is not documented and it's only used by the SDKs.