Add -trimpath flag to the builds (#13348)

Go 1.13 introduced this new flag which removes all absolute file system paths
from the binary and just keeps the module path / GOPATH. To debug binary
crashes or stack traces, we only need the path to the code and not the full
file path. Hence this is a quick way to reduce the binary size without any information
loss.

Shaves off around 750KB from the server binary.

build/release.mk

@@ -3,15 +3,15 @@ dist: | check-style test package
 
 build-linux:
 	@echo Build Linux amd64
-	env GOOS=linux GOARCH=amd64 $(GO) install -i $(GOFLAGS) -ldflags '$(LDFLAGS)' ./...
+	env GOOS=linux GOARCH=amd64 $(GO) install $(GOFLAGS) -trimpath -ldflags '$(LDFLAGS)' ./...
 
 build-osx:
 	@echo Build OSX amd64
-	env GOOS=darwin GOARCH=amd64 $(GO) install -i $(GOFLAGS) -ldflags '$(LDFLAGS)' ./...
+	env GOOS=darwin GOARCH=amd64 $(GO) install $(GOFLAGS) -trimpath -ldflags '$(LDFLAGS)' ./...
 
 build-windows:
 	@echo Build Windows amd64
-	env GOOS=windows GOARCH=amd64 $(GO) install -i $(GOFLAGS) -ldflags '$(LDFLAGS)' ./...
+	env GOOS=windows GOARCH=amd64 $(GO) install $(GOFLAGS) -trimpath -ldflags '$(LDFLAGS)' ./...
 
 build: build-linux build-windows build-osx