Replace InfluxDB with Prometheus InfluxDB exporter

The MR replaces InfluxDB with Prometheus InfluxDB exporter. Per documentation it needs the port 9122.

The MR also updates the current performance testing dashboards.

The change was validated on 3k environment:

• GPT results dashboard: http://3k.testbed.gitlab.net/-/grafana/d/J0ysCtCWz/gpt-test-results?orgId=1
• GitLab Performance SiteSpeed results dashboard: http://3k.testbed.gitlab.net/-/grafana/d/jH6yoWVMz/gitlab-performance-sitespeed-results?orgId=1

Follow-ups:

• Create snapshots for all RA environments: 1k, 2k, 3k, 5k, 10k, 25k, 50k
• Create wiki pages with past results for all RA envs under https://gitlab.com/gitlab-org/quality/performance/-/wikis/Past-Results
• Update all GPT and SiteSpeed schedules to use new InfluxDB url (change 8086 port to 9122)
• Create a sister-MR in GPT to mention Prometheus InfluxDB exporter

Related #98 (closed)