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 remove outdated "init" scripts, only keep one in sysvinit, gentoo dir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
This PR adds gitea-mixin, configurable Grafana dashboards (and potentially prometheus alerts+recording rules) based on Gitea [metrics](https://docs.gitea.io/en-us/config-cheat-sheet/#metrics-metrics).
The overview dashboard is described using jsonnet and grafonnet library: https://grafana.github.io/grafonnet-lib/
Mixins help to define dashboard and alerts as code so they can be collaboratively improved by the users.

__
## Generate config files
You can manually generate dashboards, but first you should install some tools:
```bash
go get github.com/jsonnet-bundler/jsonnet-bundler/cmd/jb
go get github.com/google/go-jsonnet/cmd/jsonnet
# or in brew: brew install go-jsonnet
```
For linting and formatting, you would also need `mixtool` and `jsonnetfmt` installed. If you
have a working Go development environment, it's easiest to run the following:
```bash
go get github.com/monitoring-mixins/mixtool/cmd/mixtool
go get github.com/google/go-jsonnet/cmd/jsonnetfmt
```
The files in `dashboards_out` need to be imported
into your Grafana server. The exact details will be depending on your environment.
Edit `config.libsonnet` (for example, list of Gitea metrics to be shown under stats can be adjusted). if required and then build JSON dashboard files for Grafana:
```bash
make
```
For more about mixins, please see:
https://github.com/monitoring-mixins/docshttps://www.youtube.com/watch?v=GDdnL5R_l-Y* add gitea mixin
* remove alerts/rules
* gitea-mixin: add interval factor of 1/2 to remove duplicated change events
* gitea-mixin: fix changes panel, add aggregation interval for changes panel
* gitea-mixin: add totals singlestat
* gitea mixin: switch change graph to timeseries type
* add color overrides for issue labels
* bump grafonnet version
* gitea-mixin: convert graphs to timeseries
* gitea-mixin: make fmt
* gitea-mixin: add .PHONE in Makefile
* gitea-mixin: add time configration
* gitea-mixin: make fmt and collapse addPanel grid
* gitea-mixin: add static ids for shared panels
* gitea-mixin: add flags showIssuesByRepository, showIssuesByLabel to show/hide corresponding panels
* gitea-mixin: update aggregation interval
* gitea-mixin: update defaults
* gitea-mixin: update panel names
* rename dir to gitea-monitoring-mixin
* gitea-mixin: add gitea_issues_open, gitea_issues_closed metrics
* gitea-mixin: update visible name for datasource
* gitea-mixin: update README
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: zeripath <art27@cantab.net>