## What changed?
~Enforce `temporal/cmd/tools/protogen` to set the PATH to point to the
locally installed tools in `.bin`.~
Enforce `temporal/cmd/tools/protogen` to use locally installed protoc
plugins.
## Why?
Without this, it will use whatever is on the PATH; which might not be
the same as in `.bin`.
## How did you test it?
- [ ] built
- [x] run locally and tested manually
- [ ] covered by existing tests
- [ ] added new unit test(s)
- [ ] added new functional test(s)
Without this change, I get different `.pb.go` files emitted as my global
proto-gen-go is used.