test_runner: remove unused shuffleArrayWithSeed #7891

Job	Run time
Build slim tarball	1m 26s
aarch64-darwin: with shared libraries	27m 24s
aarch64-linux: Cache V8 build	24s
x86_64-linux: with shared libraries	27m 9s
x86_64-darwin: with shared libraries	36m 27s
aarch64-linux: with shared openssl-4.0.0	23m 36s
aarch64-linux: with shared openssl-3.5.6	24m 58s
aarch64-linux: with shared openssl-3.0.20	25m 4s
aarch64-linux: with shared boringssl-0.20260526.0	24m 0s
aarch64-linux: with shared openssl-1.1.1w	23m 10s
aarch64-linux: with shared openssl-3.6.2	24m 24s
	3h 58m 2s

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