[Blazor][Wasm] Disable built-in typescript target

[javiercn]

After 679ed5d I started getting build errors due to the typescript SDK not being able to load one of the tasks.

Given that we don't use it and that the recommended way is to use the typescript package, I added the following property to disable the default logic
<EnableTypeScriptNuGetTarget>true</EnableTypeScriptNuGetTarget> to bypass this issue.

[javiercn]

We can remove this once we get back into a stable train.

[mkArtakMSFT]

@javiercn what will happen if we keep this as is? If nothing, let's move this to either Backlog or even close it.

[mkArtakMSFT]

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