70bff0de8d ci: Remove incorrect code comment and cargo clean (Tobin C. Harding)
Pull request description:
Recently while trying to fix CI I (Tobin) added a call to `cargo clean` and a code comment justifying it. This was merged because while not incorrect it is redundant since calling `cargo` with different `RUSTFLAGS` triggers a rebuild.
ACKs for top commit:
apoelstra:
ACK 70bff0de8d
Kixunil:
ACK 70bff0de8d
Tree-SHA512: 5bed107aedf9d6d240fa885335bfe04099436c0d30c045554644b43a06900c415708dfcedbd27037564d296c0ab12e4c4d4dc1e25ab64b4cc07ca7b46c46628a