[SDK] View should not have a unit

[marcalff]

Fixes #3547

Changes

Please provide a brief description of the changes here.

• Removed the unit member from class View
• Removed the unit parameter from ViewFactory::Create() methods

For significant contributions please make sure you have completed the following items:

• CHANGELOG.md updated for non-trivial changes
• Unit tests have been added
• Changes in public API reviewed

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 90.02%. Comparing base (03e0452) to head (4705974).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3552      +/-   ##
==========================================
- Coverage   90.03%   90.02%   -0.01%     
==========================================
  Files         220      220              
  Lines        7069     7069              
==========================================
- Hits         6364     6363       -1     
- Misses        705      706       +1     

Files with missing lines	Coverage Δ
sdk/include/opentelemetry/sdk/metrics/view/view.h	100.00% <ø> (ø)

... and 1 file with indirect coverage changes

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[marcalff]

@lalitb

Please review, related to #2236

When the unit parameter was added in the view, this was a breaking change.
So, I assume it is ok to have a breaking change (in the SDK) to remove the view unit, instead of providing a deprecation path.

[Copilot]

Pull Request Overview

This PR removes the unit parameter from the View class and ViewFactory methods to address issue #3547. This is a breaking change that simplifies the View interface by eliminating the unit field that was apparently not needed.

• Removed the unit member variable from the View class
• Removed the unit parameter from all ViewFactory::Create() method overloads
• Updated all test files and examples to use the new API without unit parameters

Reviewed Changes

Copilot reviewed 12 out of 12 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
sdk/include/opentelemetry/sdk/metrics/view/view.h	Removed unit member variable and constructor parameter from View class
sdk/include/opentelemetry/sdk/metrics/view/view_factory.h	Removed unit parameter from ViewFactory::Create method signatures
sdk/src/metrics/view/view_factory.cc	Updated ViewFactory::Create implementations to remove unit parameter handling
sdk/test/metrics/sum_aggregation_test.cc	Updated test cases to use new View constructor without unit parameter
sdk/test/metrics/meter_test.cc	Updated test case to use new View constructor without unit parameter
sdk/test/metrics/histogram_test.cc	Updated test cases to use new View constructor without unit parameter
sdk/test/metrics/histogram_aggregation_test.cc	Updated test case to use new View constructor without unit parameter
sdk/test/metrics/histogram_aggregation_benchmark.cc	Updated benchmark to use new View constructor without unit parameter
examples/prometheus/main.cc	Updated example to use new ViewFactory::Create without unit parameter
examples/otlp/grpc_metric_main.cc	Updated example to use new ViewFactory::Create without unit parameter
examples/metrics_simple/metrics_ostream.cc	Updated example to use new ViewFactory::Create without unit parameter
CHANGELOG.md	Added entry documenting the breaking change

[lalitb]

LGTM. Thanks for the fix.