Improve error messages on SSA conflicts

[blampe]

Fixes https://github.com/pulumi/pulumi-kubernetes/issues/2968.

[github-actions[bot]]

Does the PR have any schema changes?

Looking good! No breaking changes found. No new resources/functions.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 72.22222% with 5 lines in your changes are missing coverage. Please review.

Project coverage is 29.86%. Comparing base (ee09c41) to head (85bf671).

Files	Patch %	Lines
provider/pkg/await/await.go	72.22%	4 Missing and 1 partial :warning:

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #2983      +/-   ##
==========================================
+ Coverage   29.09%   29.86%   +0.77%     
==========================================
  Files          63       63              
  Lines        8345     8353       +8     
==========================================
+ Hits         2428     2495      +67     
+ Misses       5708     5634      -74     
- Partials      209      224      +15     

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