avoid duplicate evaluation in ResolveConnectionStringReferenceAsync

[adamint]

Description

Duplicates logic from ConnectionStringReference#GetValueAsync to avoid evaluating the resource connection string expression twice.

Fixes https://github.com/dotnet/aspire/pull/7662/files/f36a730ab8fdc79867669daed643a5bc1a2a6f52#r1962999417

Checklist

• Is this feature complete?
  • Yes. Ready to ship.
  • No. Follow-up changes expected.
• Are you including unit tests for the changes and scenario tests if relevant?
  • Yes
  • No, covered by existing tests
• Did you add public API?
  • Yes
    • If yes, did you have an API Review for it?
      • Yes
      • No
    • Did you add <remarks /> and <code /> elements on your triple slash comments?
      • Yes
      • No
  • No
• Does the change make any security assumptions or guarantees?
  • Yes
    • If yes, have you done a threat model and had a security review?
      • Yes
      • No
  • No
• Does the change require an update in our Aspire docs?
  • Yes
    • Is this introducing a breaking change?
      • Yes
        • Link to aspire-docs issue (please use this breaking-change template):
      • No
        • Link to aspire-docs issue (please use this doc-idea template):
  • No

[Copilot]

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

Comments suppressed due to low confidence (1)

src/Aspire.Hosting/ApplicationModel/ExpressionResolver.cs:160

• [nitpick] The variable name 'value' is ambiguous in this context. Consider renaming it to a more descriptive name such as 'resolvedConnectionString' to improve code clarity.

var value = await ResolveInternalAsync(cs.Resource.ConnectionStringExpression).ConfigureAwait(false);

[eerhardt]

LGTM

[adamint]

/backport to release/9.1

[github-actions]

Started backporting to release/9.1: https://github.com/dotnet/aspire/actions/runs/13441849725

[adamint]

/backport to release/9.1

[github-actions]

Started backporting to release/9.1: https://github.com/dotnet/aspire/actions/runs/13442202094