Revert: Implement process and instance isolation

[jamescrosswell]

Resolves #4775

• Revert instance isolation #4775

#skip-changelog

[codecov]

Codecov Report

❌ Patch coverage is 37.03704% with 17 lines in your changes missing coverage. Please review.
✅ Project coverage is 73.80%. Comparing base (0e30c90) to head (ba32e17).

Files with missing lines	Patch %	Lines
src/Sentry/Internal/Http/CachingTransport.cs	25.00%	15 Missing ⚠️
src/Sentry/SentryOptions.cs	66.66%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4787      +/-   ##
==========================================
- Coverage   73.91%   73.80%   -0.11%     
==========================================
  Files         485      483       -2     
  Lines       17682    17547     -135     
  Branches     3494     3460      -34     
==========================================
- Hits        13070    12951     -119     
+ Misses       3755     3745      -10     
+ Partials      857      851       -6     

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