Unrolled build for rust-lang#125973

Rollup merge of rust-lang#125973 - Zalathar:pretty, r=lqd

Remove `tests/run-make-fulldeps/pretty-expanded`

This was an ancient regression test for rust-lang#12685, caused by `-Zunpretty=expanded` crashing on certain code produced by `#[derive(RustcEncodable)]`.

Given that this test predates `//@ pretty-expanded` tests, and was tied to ancient implementation details of the pretty-printer and `#[derive(RustcEncodable)]` (which the test no longer even uses), I think we can safely delete it.

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Spotted via rust-lang#125948.

Author: rust-timer