allow running auth-bearer as part of the runtime

[butonic]

While testing #1533 I wondered why this feature failed as well:

  @env-config @issue-10661
  Scenario: check extra services readiness
    Given the following configs have been set:
      | config                 | value        |
      | OC_ADD_RUN_SERVICES  | auth-bearer  |
      | AUTH_BEARER_DEBUG_ADDR | 0.0.0.0:9149 |
    When a user requests these URLs with "GET" and no authentication
      | endpoint                               | service     |
      | http://%base_url_hostname%:9149/readyz | auth-bearer |
    Then the HTTP status code of responses on all endpoints should be "200"

The auth-bearer service is not started when OC_ADD_RUN_SERVICES="auth-bearer". This pr changes that.

Maybe we should log an error if the config contains an unknown service?

[rhafer]

As auth-bearer can't do anything useful for us in the current shape, we should not allow to run it (even for testing)

[butonic]

then we should delete the code

[rhafer]

either that or finally make it useful again (#897)