refactor: npm install --production for xud

[sangaman]

Follow-up to #840 - this installs xud with the production flag to avoid installing unnecessary devDependencies.

[raladev]

• [ ] https://github.com/ExchangeUnion/xud-docker/runs/1650488392?check_suite_focus=true arm build was failed, twice.

[sangaman]

* [ ]  https://github.com/ExchangeUnion/xud-docker/runs/1650488392?check_suite_focus=true arm build was failed, twice.

Yes I foolishly overlooked that we need the typescript dependency not for compiling seedutil but just for compiling xud itself, so I'm looking into the best way to install only the typescript dependency and not the rest of the devDependencies.

[sangaman]

I'm going to close this for now, there isn't a simple/clean way to install just the dependencies needed to compile .ts files into .js - we need typescript plus most of the @types dev dependencies. The current approach of installing all dependencies, compiling, and then pruning the dev dependencies is good enough,, and the solution from the previous PR of removing the grpc-tools line without pinning it to a version should continue working even with grpc-tools version updates.