Remove unnecessary _version++ from a few places

[stephentoub]

In some collection types, resizing the backing store can affect in-flight enumerations, e.g. growing a queue will cause the implementation to relayout the elements contiguously from the beginning, which will invalidate indices stored in enumerators. But for List<T> and Stack<T>, changing the backing array doesn't impact the index stored in an enumerator, nor does it impact what the enumerator will enumerate, so these operations needn't invalidate the enumerators. List<T>'s set_Capacity and TrimExcess already didn't update the version, but its EnsureCapacity did, and Stack<T>'s TrimExcess and EnsureCapacity both updated the version. This change just removes those unnecessary increments.

Fixes #82455
Related to #81523

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Issue Details

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In some collection types, resizing the backing store can affect in-flight enumerations, e.g. growing a queue will cause the implementation to relayout the elements contiguously from the beginning, which will invalidate indices stored in enumerators. But for List<T> and Stack<T>, changing the backing array doesn't impact the index stored in an enumerator, nor does it impact what the enumerator will enumerate, so these operations needn't invalidate the enumerators. List<T>'s set_Capacity and TrimExcess already didn't update the version, but its EnsureCapacity did, and Stack<T>'s TrimExcess and EnsureCapacity both updated the version. This change just removes those unnecessary increments.

Fixes #82455
Related to #81523

Author:	stephentoub
Assignees:	-
Labels:	area-System.Collections
Milestone:	8.0.0

[eiriktsarpalis]

Thanks