fix: Make BUILD_NUMBER higher priority than CI buildnumbers (#2121)
fix: Make BUILD_NUMBER higher priority than CI buildnumbers (#2121)

This change allows having custom BUILD_NUMBERs even when running in a CI environment, without having to modify packages.json.
For instance, to have BUILD_NUMBER based on UTC timestamp instead of sequential ID, a build script only needs to do the following:
```
BUILD_NUMBER=$(date -u +"%Y%m%d%H%M%S")
```
loopline-systems/electron-builder,MariaDima/electron-builder,loopline-systems/electron-builder,electron-userland/electron-builder,develar/electron-builder,develar/electron-builder,mastergberry/electron-builder,mastergberry/electron-builder,loopline-systems/electron-builder,mastergberry/electron-builder,ledinhphuong/electron-builder,ledinhphuong/electron-builder,MariaDima/electron-builder,MariaDima/electron-builder,loopline-systems/electron-builder,ledinhphuong/electron-builder,electron-userland/electron-builder,MariaDima/electron-builder,ledinhphuong/electron-builder,ledinhphuong/electron-builder,ledinhphuong/electron-builder,develar/electron-builder,develar/electron-builder,mastergberry/electron-builder,electron-userland/electron-builder,MariaDima/electron-builder,loopline-systems/electron-builder,MariaDima/electron-builder