Remove vectorizing `smart-contracts` from `node_modules` in `docs_ai_backend`

[khannanov-nil]

Problem statement

In the near future, prod machines will no longer checkout the =nil; repo. This will be done to resolve several stability issues.

Unfortunately, there are some systems and tools that rely on the content of the =nil; repo being available to them on production machines. In docs_ai_backend, it's DB population: it uses the content of smart-contracts from the root node_modules folder of the checked out repo. If no repo is available, DB will not be populated.

Solution

Replace smart-contracts from the repo inside populatDB.js with an alternate solution that does not depend on the repo.