TinyGo should use `-gc=precise` (or have nothing and just use the default provided by tinygo)

[dgryski]

The precise collector is an improvement over the conservative one. I'm not sure why we hard-coded that gc option.

https://github.com/fastly/cli/blob/44a36f81b697be6bb916426d02176bed03522714/pkg/commands/compute/language_go.go#L30