E2E: Rename end-to-end-tests-server to grafana-server (#44249)

* Rename to grafana-server / move scripts into new directory

* Change grafana-server step command

* Change scripts paths

* Use test grabpl version

* Update run-suite script

* Further name updates

* Update grabpl version

* Update contribute/style-guides/e2e-core.md

Co-authored-by: Maria Alexandra <239999+axelavargas@users.noreply.github.com>

Co-authored-by: Maria Alexandra <239999+axelavargas@users.noreply.github.com>

scripts/grafana-server/kill-server

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+. scripts/grafana-server/variables
+
+if [ -f "$PIDFILE" ]; then
+  echo -e "Found pidfile, killing running grafana-server"
+  kill -9 `cat $PIDFILE`
+  rm $PIDFILE
+fi
+
+rm -rf scripts/grafana-server/tmp