Fix collection-optimized paths for `Batch`

[viceroypenguin]

The Batch operator contains similar problems to those addressed in issue #943/PR #946. This PR removes all collection optimizations, since they are all based on caching the collection count at initial call instead of run-time.

[viceroypenguin]

1. Oops. Wilco.
2. Will restore for now, and issue separate PR to remove them after this PR is pulled in. Discussion to be tabled until then.

[codecov[bot]]

Codecov Report

Merging #965 (5057527) into master (aefa90b) will increase coverage by 0.05%. The diff coverage is 100.00%.

:exclamation: Current head 5057527 differs from pull request most recent head 2d49f5a. Consider uploading reports for the commit 2d49f5a to get more accurate results

@@            Coverage Diff             @@
##           master     #965      +/-   ##
==========================================
+ Coverage   92.49%   92.55%   +0.05%     
==========================================
  Files         113      113              
  Lines        3424     3423       -1     
  Branches     1024     1020       -4     
==========================================
+ Hits         3167     3168       +1     
  Misses        192      192              
+ Partials       65       63       -2     

Impacted Files	Coverage Δ
MoreLinq/Batch.cs	98.07% <100.00%> (+3.73%)	:arrow_up:

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[atifaziz]

and issue separate PR to remove them after this PR is pulled in

What's the reason behind removing them at all?

[viceroypenguin]

Thanks for the follow-up, but I am afraid the test and the implementation don't look right. See my comments.

Bah! Too many branches on too many projects. :)

[atifaziz]

@viceroypenguin Any chance we can merge this soon?