[ci] fix test-frame-ui job (#2672)

The test frame ui started failing consistently on latest master [1]. I
assume it was because of a race between
https://github.com/paritytech/polkadot-sdk/pull/1343 which introduced
this warning and a PR that updated our tooling version, hence the
warnings don't match perfectly, so regenerated them with
`TRYBUILD=overwrite` as the test suggests.

[1] https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4666766

---------

Signed-off-by: Alexandru Gheorghe <alexandru.gheorghe@parity.io>

substrate/frame/support/test/tests/pallet_ui/task_condition_invalid_arg.stderr

@@ -5,6 +5,7 @@ error: unused import: `frame_system::pallet_prelude::OriginFor`
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D unused-imports` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(unused_imports)]`
 
 error[E0308]: mismatched types
   --> tests/pallet_ui/task_condition_invalid_arg.rs:35:10

substrate/frame/support/test/tests/pallet_ui/task_invalid_condition.stderr

@@ -5,6 +5,7 @@ error: unused import: `frame_system::pallet_prelude::OriginFor`
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D unused-imports` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(unused_imports)]`
 
 error[E0308]: mismatched types
   --> tests/pallet_ui/task_invalid_condition.rs:18:1

substrate/frame/support/test/tests/pallet_ui/task_invalid_list.stderr

@@ -5,6 +5,7 @@ error: unused import: `frame_system::pallet_prelude::OriginFor`
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D unused-imports` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(unused_imports)]`
 
 error[E0689]: can't call method `map` on ambiguous numeric type `{integer}`
   --> tests/pallet_ui/task_invalid_list.rs:18:1

substrate/frame/support/test/tests/pallet_ui/task_invalid_weight.stderr

@@ -5,6 +5,7 @@ error: unused import: `frame_system::pallet_prelude::OriginFor`
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: `-D unused-imports` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(unused_imports)]`
 
 error[E0308]: mismatched types
   --> tests/pallet_ui/task_invalid_weight.rs:18:1