gates: drop the player build that the player tests already compile (#719)

The land chain compiled the player build twice: `cargo build -p benilla --no-default-features`,
then `cargo test -p benilla-formats -p benilla-app --no-default-features --lib`. The test build
already compiles every line of the no-`dev` graph but the `benilla` launcher, a 17-line shim with
no `dev` seam, and `benilla-app` has no `cfg(not(test))` code, so the first step added only the
shim and a link: about two of a chain's twelve minutes. It goes from `gates.sh` and CI, and
`player-tests` carries its comment.

`check.sh` no longer says a full chain before land makes the land free: main moves in between, so
the chain ran twice.

Test: this land's own chain runs the new `gates.sh`.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

.github/workflows/ci.yml

@@ -48,7 +48,5 @@ jobs:
         run: scripts/doc-links.py
       - name: pass-span-lint
         run: scripts/pass-span-lint.py
-      - name: player-build
-        run: cargo build -p benilla --no-default-features
       - name: player-tests
         run: cargo test -p benilla-formats -p benilla-app --no-default-features --lib