Set Operator installation type for usage ping

What

Sets the installation type value for the Operator for tracking adoption and usage as mentioned in #388 (closed).

How

Sets the 'installation_type' value in the Sidekiq and Webservice ConfigMaps to 'gitlab-operator', replacing 'gitlab-helm-chart'.

Notes

The Charts also configure this in the 'geo-logcursor' chart, but we don't currently deploy that component with the Operator.

Testing

Aside from the tests added in the codebase, here is some additional testing:

Content of ConfigMap

$ kubectl get cm -n n5bc4b866 gitlab-webservice -ojson | jq '.data.installation_type'
"gitlab-operator"

$ kubectl get cm -n n5bc4b866 gitlab-sidekiq -ojson | jq '.data.installation_type'
"gitlab-operator"

Content of /srv/gitlab/INSTALLATION_TYPE

$ kubectl -n n5bc4b866 exec -i gitlab-webservice-default-756799d55c-68clm -c webservice -- cat /srv/gitlab/INSTALLATION_TYPE
gitlab-operator

$ kubectl -n n5bc4b866 exec -i  gitlab-sidekiq-all-in-1-v1-6886d8b759-q8wth -c sidekiq -- cat /srv/gitlab/INSTALLATION_TYPE
gitlab-operator

Sample payload

Closes #388 (closed)