test: make sure that marked-failing synthetics actually fail #836

Job	Run time
changes	11s
docs / gh-pages	17s
ts / test-js	53s
cpp / cpp-build (macos-15)	5m 52s
rust / coverage	5m 6s
java / test-java (ubuntu-latest)	3m 8s
rust / Test mlt-py	48s
cpp / cpp-build (ubuntu-24.04)	5m 59s
java / test-java (windows-latest)	5m 11s
rust / Test wasm	1m 38s
rust / test	9m 46s
rust / lint	1m 47s
rust / Fuzz mvt_roundtrip	4m 9s
java / test-java (macos-latest)	2m 59s
rust / check	59s
rust / Fuzz decoded_layer	4m 16s
rust / Fuzz layer	4m 19s
rust / Build @maplibre/mlt-wasm npm package	1m 42s
rust / FFI c	31s
rust / FFI kotlin	56s
rust / FFI cpp	31s
rust / Test workspace publishing using --dry-run	54s
rust / Build release binaries for x86_64-unknown-linux-gnu	1m 20s
rust / Build release binaries for x86_64-pc-windows-msvc	2m 46s
rust / Build release binaries for aarch64-unknown-linux-gnu	1m 4s
rust / Build release binaries for aarch64-apple-darwin	6m 24s
rust / ci-passed-rust	2s
ci-passed	2s
rust / release-plz	-1s
rust / Upload release binaries to GitHub releases	0s
rust / Publish @maplibre/mlt-wasm to npm	0s
	1h 13m 29s

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