Remove `pytest.mark.integration` for individual tests that already
include it in `pytestmarker` at the top.

FWIW the list of such files was found using:

        git grep --name-only 'pytestmark = pytest.mark.integration' | xargs grep '@pytest.mark.integration'

runcli: rm unused 'color' and '**extra' params

See merge request BuildStream/buildstream!1198

The only customer for 'invoke' is the 'run' method on the same class.
Make it private and simplify it's interface.

Avoid disappointment by removing unused 'color' and 'extra' parameters
from 'invoke'.

These appear to have been here to mirror the interface of
click.testing.CliRunner.invoke(), which this class replaced.

cascache: limit 'infinite' cache to volume size

Closes #906

See merge request BuildStream/buildstream!1196

Make sure we don't exceed the size of the volume when calculating an
'unlimited' quota.

Note that at present, cache_size is an estimate that will be the same
as the cache_size or larger. In my own case, I have a volume dedicated
to the cache, so it was easy for the cache_quota to exceed this. This
prevented me from running BuildStream, although I had plenty of free
space.

buildelement: rm unused 'cmd_name' argument

See merge request BuildStream/buildstream!1197

We're not using the cmd_name parameter to __run_command, and it's
redundant given that the enclosing scope already uses it in the label.
Remove it to slightly improve readability.

store full host tools command in sites.py variables check.

Closes #936

See merge request BuildStream/buildstream!1194

This allows tests importing them to have access to the commands
directly and removes the need from calling this multiple times

This also fixes multiple bugs where the paths of the tests runners
might not be canonical and tools would not get found correctly