fix(storage): do not close object descriptor span on reader completion

[bajajneha27]

Problem
AsyncObjectDescriptorConnectionTracing::Read() was wrapping the returned reader in MakeTracingReaderConnection(span_, ...). AsyncReaderConnectionTracing ends the span as soon as the reader stream finishes. Because span_ represents the storage::AsyncConnection::Open span, it was ending prematurely on the first range completion instead of staying active for the lifetime of ObjectDescriptorConnection.

Fix
Returned impl_->Read(p) directly in AsyncObjectDescriptorConnectionTracing::Read(). Individual range reads are already traced by ObjectDescriptorImpl::Read(), which creates MakeTracingObjectDescriptorReader() when tracing is enabled.

[gemini-code-assist]

Code Review

This pull request simplifies the Read method in AsyncObjectDescriptorConnectionTracing by returning the result of impl_->Read(p) directly instead of wrapping it in a tracing reader connection. It also updates the corresponding unit tests to verify single and multiple read ranges, ensuring the open span is not prematurely ended. The review feedback suggests a safer and more idiomatic C++ approach in the tests by using std::make_unique and a mutable lambda capture instead of raw pointers to prevent potential memory leaks.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.24%. Comparing base (e41509e) to head (db2efff).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #16321      +/-   ##
==========================================
- Coverage   92.25%   92.24%   -0.01%     
==========================================
  Files        2227     2227              
  Lines      209234   209248      +14     
==========================================
- Hits       193024   193018       -6     
- Misses      16210    16230      +20     

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[v-pratap]

I was running a few experiments, and with the previous code I ran the Open of async and I got the trace, attached in the screenshot. I think it is correct and expected behaviour, Can you add a screenshot of trace before and after this PR change. And please let me know if my understanding is wrong. Also the error(red bar) is expected.
Trace: link