[EXAMPLE] Clean the tracer initialization in OStream example

[ThomsonTan]

Changes

Please provide a brief description of the changes here.

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

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.66%. Comparing base (497eaf4) to head (7d28eef).
Report is 127 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #3051      +/-   ##
==========================================
+ Coverage   87.12%   87.66%   +0.55%     
==========================================
  Files         200      190      -10     
  Lines        6109     5866     -243     
==========================================
- Hits         5322     5142     -180     
+ Misses        787      724      -63     

see 124 files with indirect coverage changes

[lalitb]

What is this change for - better naming for variables ? Can we ensure it is consistent across other examples, e.g. logs_simple also follow existing naming.

[ThomsonTan]

What is this change for - better naming for variables ? Can we ensure it is consistent across other examples, e.g. logs_simple also follow existing naming.

Yes, mostly about naming. Applied the same change to logs_example. Will look other examples later.