Reduce machine count for running ceph tests

[addyess]

Overview

Ceph tests continue to run into issues on gh runners where the juju client cannot connect over ssh, perhaps b/c there are 7 VM containers in the model. We can eliminate a few machines out of the test to speed up deployment, and ease up the gh runner

Details

• remove k8s-worker charm
• let the k8s control-plane run all workloads (don't taint with a NoSchedule)
• remove one ceph-osd unit

[github-actions]

Test coverage for 593c264

coverage-report: install_deps /home/runner/work/k8s-operator/k8s-operator/charms/worker/k8s> python -I -m pip install 'coverage[toml]'
coverage-report: commands[0] /home/runner/work/k8s-operator/k8s-operator/charms/worker/k8s> coverage report
Name                                    Stmts   Miss  Cover
-----------------------------------------------------------
lib/charms/k8s/v0/k8sd_api_manager.py     270     29    89%
src/charm.py                              466    238    49%
src/cloud_integration.py                   80      3    96%
src/containerd.py                         140     16    89%
src/cos_integration.py                     33     12    64%
src/events/update_status.py                48     10    79%
src/inspector.py                           40      3    92%
src/kube_control.py                        39     31    21%
src/literals.py                             1      0   100%
src/protocols.py                           16      3    81%
src/reschedule.py                          77      4    95%
src/snap.py                               165     10    94%
src/token_distributor.py                  181    109    40%
src/upgrade.py                             31      1    97%
-----------------------------------------------------------
TOTAL                                    1587    469    70%
coverage-report: OK (1.17=setup[0.98]+cmd[0.20] seconds)
congratulations :) (1.22 seconds)

Static code analysis report

Run started:2024-11-22 21:37:28.291837

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 3422
  Total lines skipped (#nosec): 3
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):