Merge | Cleanup Pre 2005 Support in TdsParser

[MichelZ]

Now that #2839 is merged, the Pre 2005 Code can be removed from netfx to align netfx & netcore code for future merge of TdsParser.

It also removes asserts that were used to gate 2005-only code

The code does not aim to remove Pre 2005 Code from other classes

This is working towards #2953

[codecov]

Codecov Report

Attention: Patch coverage is 57.81250% with 54 lines in your changes missing coverage. Please review.

Project coverage is 72.75%. Comparing base (986cdb9) to head (b9a0e05).

Files with missing lines	Patch %	Lines
...nt/netfx/src/Microsoft/Data/SqlClient/TdsParser.cs	56.80%	54 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3085      +/-   ##
==========================================
+ Coverage   72.74%   72.75%   +0.01%     
==========================================
  Files         283      283              
  Lines       58968    58883      -85     
==========================================
- Hits        42894    42839      -55     
+ Misses      16074    16044      -30     

Flag	Coverage Δ
addons	92.58% <ø> (ø)
netcore	75.51% <100.00%> (+0.02%)	⬆️
netfx	71.21% <56.80%> (-0.01%)	⬇️

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[edwardneal]

Looks good to me. Once this PR's merged, I've got a branch ready to submit (diff - about half the size of this PR) which chases the references to TdsParser.Is2005OrNewer and SqlLoginAck.isVersion8 and removes the now-redundant code.