[type_complexity]: Fix duplicate errors

[UlazkaMateusz]

Relates to #12379

Following message was duplicated:

LL |     fn def_method(&self, p: Vec<Vec<Box<(u32, u32, u32, u32)>>>) {}
   |                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
   |
   = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`

error: very complex type used. Consider factoring parts into `type` definitions
  --> tests/ui/type_complexity.rs:55:15

Methods check_trait_item and check_fn were both checking method named def_method.
Now check_trait_item only checks methods without body.

---

changelog: [type_complexity]: Fix duplicate diagnostics

[rustbot]

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[xFrednet]

Looks good to me, nice clean change. Thank you!

@bors r+

[bors]

📌 Commit 71db2d1 has been approved by xFrednet

It is now in the queue for this repository.

[bors]

⌛ Testing commit 71db2d1 with merge 70e74b1...

[bors]

☀️ Test successful - checks-action_dev_test, checks-action_remark_test, checks-action_test
Approved by: xFrednet
Pushing 70e74b1 to master...