remove git related vars from configuration/reporting-service/variables.env.original

[vdelendik]

configuration/reporting-service/variables.env.original
it has such properties to remove when variables.env should be adjusted:
GITHUB_CLIENT_ID=
GITHUB_CLIENT_SECRET=
GITHUB_HOST=github.com

also candidate for removal:
SCM_DEFAULT_ACCOUNT_ACCESS_TOKEN=
SCM_DEFAULT_ACCOUNT_ORGANIZATION_NAME=qaprosoft
SCM_DEFAULT_ACCOUNT_REPOSITORY_NAME=carina-demo
SCM_DEFAULT_ACCOUNT_REPOSITORY_URL=https://github.com/qaprosoft/carina-demo

original ticket: zebrunner/community-edition#274

[vdelendik]

need changes on reporting back-end side as well for github related args