Remove building an intermediate service provider at startup

[bkoelman]

This PR removes building an intermediate service provider at startup, which is considered an anti-pattern, leading to occasional compatibility issues.

This unblocks use in Aspire (more specifically, its usage of AddNpgsqlDataSource, which throws an ObjectDisposedException) and fixes #1082.

While AddNpgsqlDataSource (from the Npgsql.DependencyInjection NuGet package) works in a regular API project, it fails in our integration tests (tracked at npgsql/efcore.pg#2542 (comment)).

QUALITY CHECKLIST

• Changes implemented in code
• Complies with our contributing guidelines
• N/A: Adapted tests
• N/A: Documentation updated

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (2a30f19) 90.73% compared to head (1ff3ee2) 90.74%.

Files	Patch %	Lines
...NetCore/Configuration/JsonApiApplicationBuilder.cs	96.87%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1431   +/-   ##
=======================================
  Coverage   90.73%   90.74%           
=======================================
  Files         342      344    +2     
  Lines       10982    11003   +21     
  Branches     1812     1813    +1     
=======================================
+ Hits         9965     9985   +20     
  Misses        669      669           
- Partials      348      349    +1     

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