Investigate compile time improvement tuning -T4C flag

Today we build using -T4C to use parallelism with 4 core, docker puts some hard limit and we see the message:

Using the MultiThreadedBuilder implementation with a thread count of 16

This speeds up download for sure but may add contention during compile time.

Build time is around 10min on JX let's try to reduce to -T1C to see if it helps or not.

Also, it worths to try to git clone only the branch with 50 last commits instead of everything see https://medium.com/pinterest-engineering/how-a-one-line-change-decreased-our-build-times-by-99-b98453265370