test: add empty block cases to expression suite #1427

Job	Run time
ubuntu-24.04: /usr/bin/g++-14 Debug Pthreads	10m 56s
ubuntu-24.04: /usr/bin/g++-14 Release Pthreads	23m 37s
macos-latest: clang++ Release PaRSEC	8m 13s
macos-latest: clang++ Debug Pthreads	16m 30s
ubuntu-24.04: /usr/bin/g++-14 Debug PaRSEC	19m 56s
macos-latest: clang++ Release Pthreads	21m 37s
macos-latest: clang++ Debug PaRSEC	7m 47s
ubuntu-24.04: /usr/bin/g++-14 Release PaRSEC	24m 53s
	2h 13m 29s

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