feat(core): Make Tools Agent the default Agent type, deprecate other agent types

[Cadiac]

Summary

Users have found the Agent type selection to be confusing, and in vast majority of the cases Tools Agent is the only recommended Agent type to use. To simplify the usage of this very popular node other Agent types are going to be deprecated, and on new version 1.8 Agent nodes the dropdown selection for Agent type is no longer displayed, and toolsAgent is used by default.

On old Agent node's a deprecation warning is shown.

Also added maxIterations options on all Agent node types on pre-1.8 Agent nodes, this was missing from ReAct, PlanAndExecute and SqlAgent.

Related Linear tickets, Github issues, and Community forum posts

https://linear.app/n8n/issue/ADO-2779/feature-agent-node-get-rid-of-type-drop-down

Review / Merge checklist

• PR title and summary are descriptive. (conventions)
• Docs updated or follow-up ticket created.
• Tests included.
• PR Labeled with release/backport (if the PR is an urgent fix that needs to be backported)

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

📢 Thoughts on this report? Let us know!

[mutdmour]

Looks good. I know e2e tests might fail, so approving to help you get an idea as well.

[cypress]

n8n    Run #9435

Run Properties:   Passed #9435  •  53a97e6820: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 Cadiac 🗃️ e2e/*

Project	n8n
Branch Review	ado-2779-feature-agent-node-get-rid-of-type-drop-down
Run status	Passed #9435
Run duration	04m 44s
Commit	53a97e6820: 🌳 🖥️ browsers:node18.12.0-chrome107 🤖 Cadiac 🗃️ e2e/*
Committer	Jaakko Husso
View all properties for this run ↗︎

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Test results
Failures	0
Flaky	3
Pending	5
Skipped	0
Passing	437
View all changes introduced in this branch ↗︎

[github-actions]

✅ All Cypress E2E specs passed

[mutdmour]

is this already used? testing on the test instance and it does not seem to have an effect?

[Cadiac]

no, you're right. I suppose I had mistakenly assumed the logic where these options was read and passed to the executor was generic and applied to all of these, but it was only on some.

Now actually looking into this it appears that only new place where maxIterations can be supported is ReActAgent, as the other langchain executors used on these other node types (PlanAndExecuteAgent, SqlAgent) don't seem to support it.

I'm removing maxIterations from PlanAndExecuteAgent and SqlAgent and properly passing it on ReActAgent.