main/etckeeper: split completion

Split bash and zsh completions into subpkgs
7 jobs for !2356 with etckeeper-split-comp in 3 minutes and 24 seconds
detached
Status Job ID Name Coverage
  Lint
passed #25717
docker-alpine x86_64
lint

00:00:35

 
  Build
passed #25722
aarch64 docker-alpine ci-build
build-aarch64

00:01:20

passed #25723
docker-alpine ci-build armv7
build-armv7

00:02:06

passed #25721
docker-alpine ci-build ppc64le
build-ppc64le

00:00:49

passed #25720
docker-alpine ci-build s390x
build-s390x

00:00:23

passed #25719
docker-alpine ci-build x86
build-x86

00:01:21

passed #25718
docker-alpine ci-build x86_64
build-x86_64

00:01:17