Add Docker health checks to Consul and Memcached

[philippgille]

Following the initial PR that added health checks, an improvement in #162 and the use of the health checks in #154, we should use the health checks in as many test containers as possible, to benefit from the mechanism and reduce build time in CI.

This PR adds health checks for Consul and Memcached.

As their images don't have the necessary tooling installed by default, and we don't want to execute the main server process as root, we instead run a separate docker exec command to install the required tooling, while the health checks are already running (but running into errors like "curl not found").

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (128881d) 63.64% compared to head (b6e6e82) 63.64%.

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Additional details and impacted files

@@           Coverage Diff           @@
##           master     #168   +/-   ##
=======================================
  Coverage   63.64%   63.64%           
=======================================
  Files          25       25           
  Lines        2107     2107           
=======================================
  Hits         1341     1341           
  Misses        651      651           
  Partials      115      115           

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