Issue 10382: DefaultMemoryCacheModule/DefaultMemoryCacheFactory not exported in the plugin API for 2.16.x

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Affected Version: 2.16.4

What steps will reproduce the problem?
1. Have a plugin on 2.15.x that uses DefaultMemoryCacheModule
2. Migrate to 2.16.4
3.

What is the expected output?

Be able to build

What do you see instead?

Can't build because DefaultMemoryCacheModule is not found.

Please provide any additional information below.

Seems to not be exported in the plugin API any more

gerrit $ jar -tf ~/.m2/repository/com/google/gerrit/gerrit-plugin-api/2.15.9/gerrit-plugin-api-2.15.9.jar | grep DefaultMem
com/google/gerrit/server/cache/mem/DefaultMemoryCacheFactory$1.class
com/google/gerrit/server/cache/mem/DefaultMemoryCacheFactory.class
com/google/gerrit/server/cache/mem/DefaultMemoryCacheModule.class

gerrit $ jar -tf ~/.m2/repository/com/google/gerrit/gerrit-plugin-api/2.16.4/gerrit-plugin-api-2.16.4.jar | grep DefaultMem