fix util docker build - port to master

[j1010001]

port of #5750 to master

[tarakby]

@j1010001 I wanted to confirm the new behaviour is intended: there are two different images related to the new flag osusergo that our scripts build:

• default images apply the tag osusergo via the docker variable TAGS
• images we usually call "without-netgo" (used by some node operators), that overwrite TAGS (here for instance), and that disables the flag osusergo.

Is it intended that the "without-netgo" images disable osusergo ?

[turbolent]

@tarakby We had problems building static binaries that would work on GCP, and adding osusergo fixed the problem. So from what I can tell it should always be added, but am not sure

[tarakby]

If that's the case then the Dockerfile should be fixed to always hardcode osusergo and avoid it being overwritten.