kube-prometheus/Makefile: Change target output from files to folder

RemoteWriteSpec Expose QueueConfig Parameters (#1488)

Previously the `manifests` and `vendor` folder content has been build
via `manifests/**` and `vendor/**` target definitions. This results in
two issues:

1. The GNU Make recipe is executed for every single file in the folders.

2. Not all timestamps inside the `manifests` folder would be updated on
every run, thereby needing to be rerun on all following target
executions.

Solution:

1. Define the target based on the folder, not individual files

2. Remove target folder before execution recipe to ensure all timestamps
are updated.

kube-prometheus: Run node-exporter in host network

Node exporter needs to run in the host network, not in the pod network
in order to pick up network metrics of the node.

*: Refactor build system

- Move prometheus-config-reloader to cmd/
- Refactor Makefile & contrib/kube-prometheus/Makefile
- Only execute a target if its dependencies changed
  - Create empty target file for docker builds
- Replace promu with plain static `go build`

kube-prometheus: Use 1 ConfigMap per Grafana dashboard

NodeDiskRunningFull ignore etc files mountpoints

*: Use all jsonnet from master branch

Added section about grafana config

* Ignores '/etc/resolv.conf', '/etc/hosts' and '/etc/hostname' mountpoints
* Otherwise 3 additional alerts are generated

89fc4e306972604eba2dcb961a6d29cc27a668ad introduced the new Prometheus
rule file custom resource definition. This patch adjusts the
kube-prometheus project to use the new custom resource definition.

kube-prometheus: Remove duplicate unused files