[CI] tests run under cloverage on 2gb heap size JVM fail with issues in the mock ES node

[konstan]

sixsq.nuvla.server.resources.common.std-crud - unexpected status code (500) when creating configuration/nuvla resource: 
{:status 500, :headers {"Content-Type" "application/json"}, :body {:status 500, :message "unexpected error occurred: 
unexpected exception: {:root_cause [{:type \"circuit_breaking_exception\", :reason \"[parent] Data too large, data for 
[<http_request>] would be [1736238200/1.6gb], which is larger than the limit of [1731303833/1.6gb], real usage: 
[1736237568/1.6gb], new bytes reserved: [632/632b]\", :bytes_wanted 1736238200, :bytes_limit 1731303833, :durability 
\"TRANSIENT\"}], :type \"circuit_breaking_exception\", :reason \"[parent] Data too large, data for [<http_request>] would be 
[1736238200/1.6gb], which is larger than the limit of [1731303833/1.6gb], real usage: [1736237568/1.6gb], new bytes 
reserved: [632/632b]\", :bytes_wanted 1736238200, :bytes_limit 1731303833, :durability \"TRANSIENT\"}"}}

The current workaround in GHA is to set

          export JAVA_OPTS="-Xms6g -Xmx6g"
          export ES_JAVA_OPTS="-Xms6g -Xmx6g"

before running sonar-scanner.

• Note: With the config above, the time taken by the sonar-scanner increased twice. For the builds, the GHA runner used is ubuntu-latest which is 2CPU/7GBRAM and 4GB of swap. There might be swapping happing that slows down the build. This needs to be investigated

[konstan]

Consider updating mock ES node settings
https://github.com/nuvla/api-server/blob/master/code/test/sixsq/nuvla/server/resources/lifecycle_test_utils.clj#L356