update test packages and global.json to net8.0 rc.2

[vishweshbankwar]

Fixes #
Design discussion issue #

Changes

Updates test packages to rc.2 and global.json min version.

Please provide a brief description of the changes here.

Merge requirement checklist

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

[codecov]

Codecov Report

Merging #5000 (9bfe9ed) into main (74ad003) will decrease coverage by 0.10%.
Report is 2 commits behind head on main.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main    #5000      +/-   ##
==========================================
- Coverage   83.45%   83.35%   -0.10%     
==========================================
  Files         295      295              
  Lines       12339    12339              
==========================================
- Hits        10297    10285      -12     
- Misses       2042     2054      +12     

Flag	Coverage Δ
unittests	83.35% <ø> (-0.10%)	⬇️

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see 9 files with indirect coverage changes