* eos can not check config without config session support
* add testcase for check_mode without config session
* fix eos eapi to read use_session env var
Fixes#36979
If `abort` is not issued in the top level session prompt
the existing session goes to pending state.
The fix is to come out of config mode by issuing `end` command
and again to same config session and execute `abort` which
`abort` is issued at the top level session prompt.