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>

scripts/check.sh

@@ -92,7 +92,7 @@ esac
 pflags=""
 for p in $pkgs; do pflags="$pflags -p $p"; done
 echo "check: scope = $pkgs"
-echo "check:   (changed crates + everything that depends on them; full chain still runs at sync→land)"
+echo "check:   (changed crates + everything that depends on them; the full chain runs once, at land)"
 
 log="$(mktemp "${TMPDIR:-/tmp}/benilla-check.XXXXXX")"
 skips="$(mktemp "${TMPDIR:-/tmp}/benilla-check-skips.XXXXXX")"
@@ -120,4 +120,4 @@ if [ -s "$skips" ]; then
 fi
 
 echo "CHECK GREEN (scoped: $pkgs)"
-echo "  (land still pays the full chain once: scripts/gates.sh — memoized, so an already-gated tree is free)"
+echo "  (the full chain, scripts/gates.sh, runs once on the tree that lands; a run before it repeats it)"