remove legacy and redundant build-tags

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

Author: thaJeztah

cli/command/container/completion.go

@@ -1,6 +1,5 @@
 // FIXME(thaJeztah): remove once we are a module; the go:build directive prevents go from downgrading language version to go1.16:
 //go:build go1.22
-// +build go1.22
 
 package container
 

cmd/docker/internal/signals/signals_unix.go

@@ -1,6 +1,3 @@
-//go:build unix
-// +build unix
-
 package signals
 
 import (