Shutdown cache

[actiontech-bot]

Raised by: @yanhuqing666

1. Question: if primary-key-cache and routing-cache are not configured, does Dble work fine?

2. If Dble doesn't work, following changes are required:

   • 2.1, if routing-cache isn't configured, disable it.
   • 2.2, for primary-cache, there are 4 states :
     • 2.2.1, there is default primary-key-cache, and specific primary-key-cache too
     • 2.2.2, there is default primary-key-cache, but there is no specific primary-key-cache
     • 2.2.3, there is no default primary-key-cache, but there is specific primary-key-cache
     • 2.2.4, there is no default primary-key-cache, nor primary-key-cache

[zhunina]

done