documenting reason for skipping test TestConsensus_LeaderForView (after current epoch)

[AlexHentschel]

This PR covers the quarantined test (see Notion doc Flaky and Skipped Tests - Quarantine for details):

flow-go/consensus/hotstuff/committees/consensus_committee_test.go

Lines 141 to 147 in c3502d1

	t.Run("after current epoch", func(t *testing.T) {
	t.SkipNow()
	// get leader for view in next epoch when it is not set up yet
	_, err := committee.LeaderForView(250)
	assert.Error(t, err)
	assert.True(t, errors.Is(err, protocol.ErrNextEpochNotSetup))
	})

While the test is skipped for a valid reason (it tests the behaviour of the mature protocol, which is different than the current implementation due to a temporary fallback), but this reasoning is not documented in the code.

This PR adds a comment explaining the reason for skipping the test.

• no algorithmic changes
• test remains skipped
• note: there is a separate test for covering the temporary logic

[jordanschalm]

Thank you 🙏

[huitseeker]

This may not be within scope of this PR, but is there a way that :

• the presence or absence of EECC
• the presence of absence of a test targeting EECC
  ... in the source could be maintained in sync using a build tag, rather than a skipped test?

[codecov-commenter]

Codecov Report

Merging #1342 (76ca57a) into master (2a21b49) will decrease coverage by 0.03%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1342      +/-   ##
==========================================
- Coverage   56.29%   56.26%   -0.04%     
==========================================
  Files         502      502              
  Lines       31208    31208              
==========================================
- Hits        17570    17560      -10     
- Misses      11263    11275      +12     
+ Partials     2375     2373       -2     

Flag	Coverage Δ
unittests	56.26% <ø> (-0.04%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
...sus/approvals/assignment_collector_statemachine.go	42.30% <0.00%> (-9.62%)	⬇️

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[gomisha]

thank you for clarifying why the test needs to be skipped and updating quarantine list with this PR - much clearer.