Do not suggest using -Zmacro-backtrace for builtin macros

For macros that are implemented on the compiler, or that are annotated with `rustc_diagnostic_item`, which have arbitrary implementations from the point of view of the user and might as well be intrinsics, we do *not* mention the `-Zmacro-backtrace` flag. This includes `derive`s and standard macros like `panic!` and `format!`.

Author: estebank

tests/ui/asm/x86_64/type-check-2.stderr

@@ -21,7 +21,6 @@ LL |         asm!("{}", in(reg) vec![0]);
    |                            ^^^^^^^
    |
    = note: only integers, floats, SIMD vectors, pointers and function pointers can be used as arguments for inline assembly
-   = note: this error originates in the macro `vec` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: cannot use value of type `(i32, i32, i32)` for inline assembly
   --> $DIR/type-check-2.rs:48:28

tests/ui/associated-consts/defaults-not-assumed-fail.stderr

@@ -23,8 +23,6 @@ note: erroneous constant encountered
    |
 LL |     assert_eq!(<() as Tr>::B, 0);    // causes the error above
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
-   |
-   = note: this note originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 note: erroneous constant encountered
   --> $DIR/defaults-not-assumed-fail.rs:33:5
@@ -33,7 +31,6 @@ LL |     assert_eq!(<() as Tr>::B, 0);    // causes the error above
    |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    |
    = note: duplicate diagnostic emitted due to `-Z deduplicate-diagnostics=no`
-   = note: this note originates in the macro `assert_eq` (in Nightly builds, run with -Z macro-backtrace for more info)
 
 error: aborting due to 1 previous error