Install Times Could Still uses Cache

[AlexanderKaran]

Feedback from NextJS Team:

Medium: install timing is not a well-defined cold install.
The runner removes node_modules, but reuses a global pnpm store, ignores store-prune failures, runs all repetitions in the same directory, and uses
--no-frozen-lockfile (
is run-install-benchmark.ts (line 22)).
This can mix one network-heavy run with cached runs and permits lockfile repair or dependency resolution
during measurement.

Part of #195

[AlexanderKaran]

I also updated the approach of build times to copy this.

Whats funny is on average install and build times (cold and warm) have all got slightly faster....... which is interesting.