[test][execution] Move conda related helper out of class

That will make them re-usable in other tests like
in beat/beat.cmdline>
8 jobs for test_execution_extract_helper_methods in 54 minutes and 53 seconds (queued for 7 seconds)
Status Job ID Name Coverage
  Build
passed #176208
docker-build
build_linux_36

00:16:38

65.0%
passed #177167
docker-build
build_linux_37

00:14:29

65.0%
passed #176360
macosx
build_macosx_36

00:21:10

64.0%
passed #176207
macosx
build_macosx_37

00:19:14

64.0%
canceled #176379
docker-build
build_linux_37

24:05:21

failed #176824
docker-build
build_linux_37

00:00:08

failed #176209
docker-build
build_linux_37

00:15:57

65.0%
failed #176206
macosx
build_macosx_36

00:18:54

64.0%