[CIVIS-8333] better handling of test.type and span.kind tags

[anmarchenko]

What does this PR do?

• We no longer send test.type tag for session, modules, and suites as per citestcycle spec.
• Ext::Test::SPAN_KIND_TEST constant is introduced to make clear that span.kind is not the same as type.
• SPECIAL_TAGS is renamed to TRANSIENT_TAGS to communicate that these tags are not making it to backend
• test.type tag has value "test" by default so we don't have to set it in each of the contrib integrations

Motivation

• fix spec issue: we currently send test.type tag for session, modules, suites but citestcycle spec says that test.type is only for test events
• span.kind purpose was confusing
• some tag constant names were suboptimal

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (8dd092a) 99.10% compared to head (af2d55f) 99.10%.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #106      +/-   ##
==========================================
- Coverage   99.10%   99.10%   -0.01%     
==========================================
  Files         149      149              
  Lines        6383     6374       -9     
  Branches      277      277              
==========================================
- Hits         6326     6317       -9     
  Misses         57       57              

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