GEODE-8637 changed Geode's Gradle build script to give each test worker JVM its own, unique working directory, and to copy the default gemfire.properties file into each working directory.
When a test will be run in docker, docker.gradle further differentiates each test worker JVM's working directory by appending the Gradle worker ID.
GEODE-8637 made this unnecessary, but did not edit docker.gradle to stop appending the worker ID.
As a result, running dockerized tests creates unnecessary directories, and executes each test in a directory that lacks the default gemfire.properties.
Solution: Change docker.gradle to stop appending the worker ID onto the already unique working directory name.