Auto merge of #10866 - Muscraft:update-extra-link-tests, r=ehuss

Auto merge of #10866 - Muscraft:update-extra-link-tests, r=ehuss

remove `.masquerade_as_nightly_cargo()` from build_script_extra_link_arg.rs

When looking at making [`.masquerade_as_nightly_cargo()` take in a list of reasons](https://rust-lang.zulipchat.com/#narrow/stream/246057-t-cargo/topic/problems.20finding.20.60.2Emasquerade_as_nightly_cargo.28.29.60), I found that [`build_script_extra_link_arg.rs`](https://github.com/rust-lang/cargo/blob/8827baaa781b37872134c1ba692a6f0aeb37890e/tests/testsuite/build_script_extra_link_arg.rs) still was using it. `extra-link-arg` was [stabilized in 1.56.0](https://github.com/rust-lang/cargo/blob/8827baaa781b37872134c1ba692a6f0aeb37890e/src/doc/src/reference/unstable.md#extra-link-arg), so this PR removes `.masquerade_as_nightly_cargo()` from all the tests in this file.