Installation documentation: obsolete docker environment variables?

[wagner-intevation]

These three environment variables seem to have no effect: https://github.com/certtools/intelmq/blob/79cae294a74ab77f09b1f371a19f04ad65abab12/docs/user/installation.rst#L190 https://github.com/certtools/intelmq/blob/79cae294a74ab77f09b1f371a19f04ad65abab12/docs/user/installation.rst#L192 https://github.com/certtools/intelmq/blob/79cae294a74ab77f09b1f371a19f04ad65abab12/docs/user/installation.rst#L194 IIRC they were made obsolete by the generic solution to set parameters with env variables (INTELMQ_SOURCE_PIPELINE_HOST etc.)

[waldbauer-certat]

@wagner-intevation

INTELMQ_PIPELINE_HOST is being used, but INTELMQ_SOURCE_PIPELINE_BROKER, INTELMQ_DESTIONATION_PIPELINE_BROKER, INTELMQ_SOURCE_PIPELINE_HOST, INTELMQ_DESTINATION_PIPELINE_HOST and INTELMQ_REDIS_CACHE_HOST are not used.

PR is on the way