chore: clean up "contrib" dir (#37690)

1. remove useless files like "backport.go", "update_dependencies.sh"
2. remove outdated "init" scripts, only keep one in sysvinit, gentoo dir
is also kept because it still uses openrc
3. move "service" related config and scripts into "service" directory

build/test-env-check.sh

@@ -1,24 +0,0 @@
-#!/bin/sh
-
-set -e
-
-if [ ! -f ./build/test-env-check.sh ]; then
-  echo "${0} can only be executed in gitea source root directory"
-  exit 1
-fi
-
-
-echo "check uid ..."
-
-# the uid of gitea defined in "https://gitea.com/gitea/test-env" is 1000
-gitea_uid=$(id -u gitea)
-if [ "$gitea_uid" != "1000" ]; then
-  echo "The uid of linux user 'gitea' is expected to be 1000, but it is $gitea_uid"
-  exit 1
-fi
-
-cur_uid=$(id -u)
-if [ "$cur_uid" != "0" -a "$cur_uid" != "$gitea_uid" ]; then
-  echo "The uid of current linux user is expected to be 0 or $gitea_uid, but it is $cur_uid"
-  exit 1
-fi

build/test-env-prepare.sh

@@ -1,11 +0,0 @@
-#!/bin/sh
-
-set -e
-
-if [ ! -f ./build/test-env-prepare.sh ]; then
-  echo "${0} can only be executed in gitea source root directory"
-  exit 1
-fi
-
-echo "change the owner of files to gitea ..."
-chown -R gitea:gitea .