Scala.js targets fullLinkJS and fastLinkJS does not respect silent mode

[carlosedp]

Running mill with silent and disable-ticker mode, still prints output to console (on success):

❯ mill -s --disable-ticker frontend.fullLinkJS
[info] compiling 1 Scala source to repos/scala-playground/zio-scalajs-stack/out/frontend/compile.dest/classes ...
[info] done compiling
Linker: Compute reachability: 419107 us
Linker: Assemble LinkedClasses: 24123 us
Linker: 474801 us
Optimizer: Batch mode: true
Optimizer: Incremental part: 151552 us
Optimizer: Optimizing 8124 methods.
Optimizer: Optimizer part: 689155 us
Optimizer: 850909 us
Refiner: Compute reachability: 79216 us
Refiner: Assemble LinkedClasses: 6955 us
Refiner: 97589 us
Module Splitter: Calculate Dependency Info: 2797 us
Module Splitter: Analyze Modules: 53800 us
Module Splitter: Assemble Modules: 9472 us
Module Splitter: 67405 us
Emitter: Generate Classes: 612803 us
Emitter: Write trees: 35800 us
Emitter: Class tree cache stats: reused: 0 -- invalidated: 744
Emitter: Method tree cache stats: reused: 0 -- invalidated: 4151
Emitter: 676614 us
BasicBackend: Write result: 307168 us

It's expected no output is generated from logs.

Use case: I have a user-defined task that prints out the generated files full-path that is sent to another process input. This issue impacts this since all output (printed above) is sent to the other process together with the path.