Improve "resolution failed" error

[roberth]

Change the last line of the error (the exception). Previously:

error: Cannot build '/nix/store/cqc798lwy2njwbdzgd0319z4r19j2d1w-nix-manual-2.33.0pre20251101_e4e4063.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/f1kln1c6z9r7rlhj0h9shcpch7j5g1fj-nix-manual-2.33.0pre20251101_e4e4063-man
         /nix/store/k65203rx5g1kcagpcz3c3a09bghcj92a-nix-manual-2.33.0pre20251101_e4e4063
error: Cannot build '/nix/store/ajk2fb6r7ijn2fc5c3h85n6zdi36xlfl-nixops-manual.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/0anr0998as8ry4hr5g3f3iarszx5aisx-nixops-manual
error: resolution failed

Now:

error: Cannot build '/nix/store/cqc798lwy2njwbdzgd0319z4r19j2d1w-nix-manual-2.33.0pre20251101_e4e4063.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/f1kln1c6z9r7rlhj0h9shcpch7j5g1fj-nix-manual-2.33.0pre20251101_e4e4063-man
         /nix/store/k65203rx5g1kcagpcz3c3a09bghcj92a-nix-manual-2.33.0pre20251101_e4e4063
error: Cannot build '/nix/store/ajk2fb6r7ijn2fc5c3h85n6zdi36xlfl-nixops-manual.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/0anr0998as8ry4hr5g3f3iarszx5aisx-nixops-manual
error: Build failed due to failed dependency

Motivation

Hardly anyone knows what "resolution failed" means.
Keep it understandable for users.

Context

• Introduced in Reapply the rest of #14022 #14225

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