cleanup: remove unused pre-methods from the ContractNegotiationListener

[janpmeyer]

What this PR changes/adds

The pre-methods of the Interface ContractNegotiationListener were removed. Therefore also the classes
AbstractContractNegotiationManager, ConsumerContractNegotiationManager and ProviderContractNegotiationManager are being touched publishing the "pre-Events".

Also the ContractNegotiationTest is touched, because it was checking about right publishing of pre-events.

Why it does that

Like in PR #1609 discussed and in Issue #1649 addressed the pre-methods arent used in the project and should be removed.

Linked Issue(s)

Closes #1649

Checklist

• added appropriate tests?
• performed checkstyle check locally?
• added/updated copyright headers?
• documented public classes/methods?
• added/updated relevant documentation?
• added relevant details to the changelog? (skip with label no-changelog)
• formatted title correctly?

[codecov-commenter]

Codecov Report

Merging #1659 (e690125) into main (9085e5e) will increase coverage by 0.05%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #1659      +/-   ##
==========================================
+ Coverage   67.83%   67.88%   +0.05%     
==========================================
  Files         782      782              
  Lines       16809    16795      -14     
  Branches     1062     1062              
==========================================
- Hits        11403    11402       -1     
+ Misses       4923     4910      -13     
  Partials      483      483              

Impacted Files	Coverage Δ
...gotiation/observe/ContractNegotiationListener.java	0.00% <ø> (ø)
...egotiation/AbstractContractNegotiationManager.java	94.11% <100.00%> (-0.07%)	⬇️
...iation/ConsumerContractNegotiationManagerImpl.java	87.38% <100.00%> (ø)
...iation/ProviderContractNegotiationManagerImpl.java	90.55% <100.00%> (ø)

---

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 9085e5e...e690125. Read the comment docs.