[release/8.0-preview4] [blazor] Drop explicit change of extension of assembly to lazy load

[github-actions]

Backport of #47901 to release/8.0-preview4

/cc @maraf

[blazor] Drop explicit change of extension of assembly to lazy load

Description

• In [blazor] Use JSImport for lazy loading assemblies #46437 made an explicit change of extension of assembly to lazy load to .dll
• This change now conflicts with support for .webcil
• The assembly (file) name comes from the user and it's validated before that it points to an existing file, so the explicit change of extension is void even for .dll scenario (the user must have provided name with .dll)
• It would be better if users would be providing only assembly name, without extension at all, incuding BlazorWebAssemblyLazyLoad MSBuild item, but that is probably a breaking change

I would like to backport this change to preview4 if possible, so that webcil support is complete

Customer Impact

Fix support for lazy assembly loading in webcil format

Regression?

• Yes
• No

Risk

• High
• Medium
• Low

[Justify the selection above]

Verification

• Manual (required)
• Automated

Packaging changes reviewed?

• Yes
• No
• N/A

---

When servicing release/2.1

• Make necessary changes in eng/PatchConfig.props

[ghost]

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[ghost]

Hi @github-actions[bot]. This PR was just approved to be included in the upcoming servicing release. Somebody from the @dotnet/aspnet-build team will get it merged when the branches are open. Until then, please make sure all the CI checks pass and the PR is reviewed.