[Performance]: BuildEventArgsWriter.WriteProjectItems spends a large % CPU time on CopyOnWriteDictionary

### Issue Description

While profiling BinaryReader/Writer, I have noticed a large % of time in creating CopyOnWriteDictionary/ImmutableDictionary. This event is triggered from LogProjectEvaluationFinished() where it enumerates through all the items and metadata. This is a lot of data but it should not be as much seen. The time is spent in creating the list of metadata using CopyOnWriteDictionary/ImmutableDictionary but it discard shortly afterwards.

### Steps to Reproduce

I used a medium to large solution of 200-300 projects to run the `clean` target (on an already cleaned build). This focuses the time spent on Project Evaluations.

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### Data


### Analysis

I have commented out the writer of `foreach (var kvp in item.EnumerateMetadata())` in BuildEventArgsWriter.cs. The repro improved from 10s to 6s. It is hard to confirm if 6s is correct final performance, as there are a lot of Lazy or delayed evaluations, but it should be closer to 6s or 7s than 10s.

### Versions & Configurations

_No response_

### Regression

- [ ] yes
- [X] no

### Regression Details

No, but it is hard to confirm as this is my first time profiling this code path.