refactor: remove deprecated types in random_string() helper #13342

Job	Run time
Setup PHP Version for Code Coverage	2s
Others (8.4) / Sanity Tests	2m 16s
Others (8.3) / Sanity Tests	2m 18s
Others (8.1) / Sanity Tests	2m 33s
Others (8.2) / Sanity Tests	2m 33s
DatabaseLive	0s
CacheLive	0s
Upload coverage results to Coveralls	0s
SeparateProcess	0s
	9m 42s

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