[Metrics API] Update Instrument Provider and remove try_init methods

[utpilla]

Towards #1699

Changes

• Update InstrumentProvider trait methods to return the individual instruments instead of a Result
• Remove try_init methods from the all the instrument builders

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)

[codecov]

Codecov Report

Attention: Patch coverage is 58.19672% with 51 lines in your changes missing coverage. Please review.

Project coverage is 79.1%. Comparing base (f45e840) to head (b82eaac).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
opentelemetry/src/metrics/mod.rs	0.0%	32 Missing ⚠️
opentelemetry-sdk/src/metrics/meter.rs	77.9%	19 Missing ⚠️

Additional details and impacted files

@@          Coverage Diff          @@
##            main   #2227   +/-   ##
=====================================
  Coverage   79.1%   79.1%           
=====================================
  Files        121     121           
  Lines      21184   21171   -13     
=====================================
- Hits       16772   16762   -10     
+ Misses      4412    4409    -3     

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