Remove redundant code in hmc.jl

[sunxd3]

The removed lines should be covered by the combination of

Turing.jl/src/mcmc/abstractmcmc.jl

Lines 38 to 39 in b3a13a1

	getstats(transition::AdvancedHMC.Transition) = transition.stat

and

Turing.jl/src/mcmc/Inference.jl

Lines 225 to 230 in b3a13a1

	function Transition(model::DynamicPPL.Model, vi::AbstractVarInfo, t)
	θ = getparams(model, vi)
	lp = getlogp(vi)
	return Transition(θ, lp, getstats(t))
	end

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.83%. Comparing base (3c91eec) to head (b3a13a1).
Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2357      +/-   ##
==========================================
- Coverage   86.86%   86.83%   -0.04%     
==========================================
  Files          24       24              
  Lines        1599     1595       -4     
==========================================
- Hits         1389     1385       -4     
  Misses        210      210              

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[coveralls]

Pull Request Test Coverage Report for Build 11124105939

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.03%) to 87.052%

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Totals
Change from base Build 11050401755:	-0.03%
Covered Lines:	1385
Relevant Lines:	1591

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💛 - Coveralls