remove nested yarn.lock file
remove nested yarn.lock file

Summary: my understanding of workspaces (https://yarnpkg.com/lang/en/docs/workspaces/) is that we should not have nested lock files. the one in flow/yarn.lock should be the only one.

Reviewed By: zertosh

Differential Revision: D16262622

fbshipit-source-id: 29925b552a4afa200090c78c01197ceb246c1fe7

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow