chore: removed dedicated targetManager config

[puffitos]

Motivation

Part of #63

Changes

• Removed the tm-config flags
• Renamed the configuration of targetmanager to targetManager (YAML-conformity)
• Updated docs

Tests done

• [x] couple of binary runs with the targetManager config in the default startupconfig file were successful
• [x] a manuall e2e helm deployment with the provided YAML resulted in a running sparrow with a gitlab target manager

values.yaml

image:
  repository: mtr.devops.telekom.de/caas/sparrow
  tag: "dev-bruno"

ingress:
  enabled: true
  hosts:
    - host: sparrow-dev.caas-s01.telekom.de
      paths:
        - path: /
          pathType: ImplementationSpecific
  tls:
    - hosts:
        - sparrow-dev.caas-s01.telekom.de
# -- startup configuration of the Sparrow
# see: https://github.com/caas-team/sparrow/blob/main/docs/sparrow_run.md
startupConfig:
   name: the-sparrow.com
   targetManager:
     checkInterval: 300s
     unhealthyThreshold: 600s
     registrationInterval: 300s
     gitlab:
       token: ""
       baseUrl: https://gitlab.com
     projectId: ""

TODO

• [x] I've assigned this PR to myself
• [x] I've labeled this PR correctly

[puffitos]

Thanks for the review @lvlcn-t , I'll fix everything tomorrow