[UI] Don't build yugabyted-ui by default in yb_build.sh

[jasonyb]

Description

yugabyted-ui is not a necessary build step in yb_build.sh, so it should not be run by default there. If we want yugabyted-ui packaged into releases by default, it should be part of the default of yb_release instead.

[jasonyb]

Closed by commit f63dfc8 (autoclose did not work).