fix(k3s): use with_tmpfs_mount to avoid duplicate tmpfs kwarg

[Tranquility2]

Problem

K3SContainer.__init__ configures tmpfs mounts via with_kwargs:

self.with_kwargs(privileged=True, tmpfs={"/run": "", "/var/run": ""})

Since #978, DockerContainer.start() also passes tmpfs=self.tmpfs explicitly to docker_client.create(), while still spreading **self._kwargs. This causes a duplicate-keyword error on every K3S container start:

TypeError: docker.models.containers.ContainerCollection.run() got multiple values for keyword argument 'tmpfs'

CI evidence: every test (3.10|3.13|3.14, k3s) job fails with this error.

Fix

Migrate to the dedicated with_tmpfs_mount() API introduced in #978, leaving only privileged=True in with_kwargs.

Verification

uv run pytest -q modules/k3s/tests/test_k3s.py no longer raises the TypeError (container starts successfully; remaining test progression depends on CI environment as before).

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 83.29%. Comparing base (be4c857) to head (ef8f498).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1034   +/-   ##
=======================================
  Coverage   83.29%   83.29%           
=======================================
  Files          16       16           
  Lines        1754     1754           
  Branches      193      193           
=======================================
  Hits         1461     1461           
  Misses        236      236           
  Partials       57       57           

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