Core: Unify display of error type prefixes

[dalexeev]

• Fixes the bug mentioned in Godot4.4dev7: Using @warning_ignore annotation at function signature level is broken #100878 (comment).

Before:

$ godot4 --headless -d -s script.gd
Godot Engine v4.3.stable.official.77dcf97d8 - https://godotengine.org

ERROR: 'The local variable "a" is declared but never used in the block. If this is intended, prefix it with an underscore: "_a".'
ERROR: 'Using assignment with operation but the variable "a" was not previously assigned a value.'

After:

$ ./godot.linuxbsd.editor.dev.x86_64 --headless -d -s script.gd
Godot Engine v4.4.dev.custom_build.56bfe4558 (2024-12-29 11:49:01 UTC) - https://godotengine.org

WARNING: The local variable "a" is declared but never used in the block. If this is intended, prefix it with an underscore: "_a".
     at: GDScript::reload (res://script.gd:4)
WARNING: Using assignment with operation but the variable "a" was not previously assigned a value.
     at: GDScript::reload (res://script.gd:5)

[Repiteo]

Needs rebase

[dalexeev]

Needs rebase

Done.

[Repiteo]

Thanks!