ci: make tests run in parallel

[artemrys]

This PR runs tests based on -k parameter in the CI, so instead of waiting > 1 hour until tests are finished, now it is 30 minutes of waiting :)

This PR also removes snyk and reorganises the overall pipeline to execute things faster.

[github-actions]

CLA Assistant Lite bot All contributors have signed the CLA ✍️ ✅

[codecov-commenter]

Codecov Report

Merging #553 (6f8c58d) into develop (eb940bc) will decrease coverage by 0.16%.
The diff coverage is n/a.

@@             Coverage Diff             @@
##           develop     #553      +/-   ##
===========================================
- Coverage    94.88%   94.72%   -0.17%     
===========================================
  Files           50       42       -8     
  Lines         2619     2557      -62     
===========================================
- Hits          2485     2422      -63     
- Misses         134      135       +1     

Impacted Files	Coverage Δ
..._tests/requirement_test_datamodel_tag_constants.py	0.00% <0.00%> (-100.00%)	⬇️
...ddon/standard_lib/addon_parser/eventtype_parser.py	96.15% <0.00%> (-0.28%)	⬇️
.../standard_lib/addon_parser/savedsearches_parser.py	96.87% <0.00%> (-0.19%)	⬇️
...don/standard_lib/addon_parser/transforms_parser.py	97.10% <0.00%> (-0.09%)	⬇️
...on/standard_lib/sample_generation/sample_stanza.py	97.22% <0.00%> (-0.02%)	⬇️
...nk_addon/standard_lib/addon_parser/props_parser.py	99.20% <0.00%> (-0.02%)	⬇️
pytest_splunk_addon/standard_lib/__init__.py	100.00% <0.00%> (ø)
...st_splunk_addon/standard_lib/app_test_generator.py	100.00% <0.00%> (ø)
...splunk_addon/standard_lib/addon_parser/__init__.py	100.00% <0.00%> (ø)
...splunk_addon/standard_lib/cim_compliance/plugin.py	100.00% <0.00%> (ø)
... and 31 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update eb940bc...6f8c58d. Read the comment docs.