[QA] single command to run all API/CLI tests

[saw-jan]

#9872 (comment)

One suggestion: maybe we can join make test-acceptance-from-core-api to make test-acceptance-api?
but keep the old set naming (prefixes with core) to use only one command to run tests:

Currently, we have two different commands to run the ocis API tests:

• make test-acceptance-api: to run API/CLI tests for local ocis tests
• make test-acceptance-from-core-api: ro run API tests taken from oc10 repo

It would be better to have a single command to run all the tests. So ti achieve this we can do the following things:

• remove command test-acceptance-from-core-api
• merge behat configs behat.yml and behat-core.yml
• use command test-acceptance-api for all tests
• update the docs