chore(deps): update vitess/vttestserver:mysql80 docker digest to 5a75cf2 #12182

Job	Run time
Test vitess_8_0 (graphql) on Linux	1m 57s
Test vitess_8_0 (json) on Linux	1m 45s
Test postgres15 (graphql) on Linux	15m 24s
Test postgres15 (json) on Linux	14m 20s
Test mssql_2022 (graphql) on Linux	8m 32s
Test mssql_2022 (json) on Linux	10m 1s
Test sqlite (graphql) on Linux	1m 55s
Test sqlite (json) on Linux	2m 1s
Test mongodb_4_2 (graphql) on Linux	3m 13s
Test mongodb_4_2 (json) on Linux	3m 33s
Test cockroach_23_1 (graphql) on Linux	27m 23s
Test cockroach_23_1 (json) on Linux	27m 13s
Test cockroach_22_2 (graphql) on Linux	16m 39s
Test cockroach_22_2 (json) on Linux	24m 14s
Test cockroach_22_1_0 (graphql) on Linux	24m 32s
Test cockroach_22_1_0 (json) on Linux	29m 47s
	3h 32m 29s

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