Fix outdated getMaxRemovalHeight

[shuse2]

What was the problem?

This PR resolves #9064

How was it solved?

• Remove duplicate getMaxRemovalHeight implementation
• Move test to the main implementation spec

How was it tested?

• Updated test

[codecov]

Codecov Report

Merging #9065 (167a78c) into release/6.0.0 (196c9ec) will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@                Coverage Diff                @@
##           release/6.0.0    #9065      +/-   ##
=================================================
- Coverage          83.52%   83.52%   -0.01%     
=================================================
  Files                603      603              
  Lines              22672    22671       -1     
  Branches            3348     3348              
=================================================
- Hits               18937    18936       -1     
  Misses              3735     3735              

Files	Coverage Δ
...ne/consensus/certificate_generation/commit_pool.ts	93.98% <100.00%> (ø)
framework/src/engine/consensus/consensus.ts	82.68% <100.00%> (-0.05%)	⬇️