Update git submodules
Update git submodules

* Update plugins/plugin-manager from branch 'master'
  to c921234cec4c0d058b35a8d117f55fce4d4c5e65
  - Bazel: Remote unused PLUGIN_DEPS variable
    
    Change-Id: I39c1dfd9d5c1a025410bbd9cdf7eec0bd76dcccd
    
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