Fix references to docker images for some databases

I just assumed some paths but didn't check them previously.

tests/docker-compose.yaml

@@ -12,7 +12,7 @@ services:
       - ./testdata/init/postgres:/docker-entrypoint-initdb.d
 
   mysql:
-    image: docker.io/library/mysql/mysql-server:8.0.27
+    image: docker.io/mysql:8.0.27
     command: ['--default-authentication-plugin=mysql_native_password', '--log_bin_trust_function_creators=1']
     restart: always
     environment:
@@ -38,7 +38,7 @@ services:
       - ./testdata/init/mysql:/docker-entrypoint-initdb.d
 
   cockroach:
-    image: docker.io/library/cockroachdb/cockroach-unstable:v23.1.0-rc.2
+    image: docker.io/cockroachdb/cockroach:v23.1.0
     environment:
       - COCKROACH_USER=jet
       - COCKROACH_PASSWORD=jet