v1.14: ci: discard misleading cargo uninstall errors in bk post-che…

…ckout hook (backport of #32139) (#32140)

ci: discard misleading `cargo uninstall` errors in bk post-checkout hook (#32139)

(cherry picked from commit 26be1a3)

Co-authored-by: Trent Nelson <trent@solana.com>

.buildkite/hooks/post-checkout

@@ -37,6 +37,6 @@ source ci/env.sh
 # HACK: These are in our docker images, need to be removed from CARGO_HOME
 #  because we try to cache downloads across builds with CARGO_HOME
 # cargo lacks a facility for "system" tooling, always tries CARGO_HOME first
-cargo uninstall cargo-audit || true
-cargo uninstall svgbob_cli || true
-cargo uninstall mdbook || true
+cargo uninstall cargo-audit &>/dev/null || true
+cargo uninstall svgbob_cli &>/dev/null || true
+cargo uninstall mdbook &>/dev/null || true