fix: fix outdated reg names in deployment samples

[ilharp]

Currently deployment samples WV2DeploymentWiXCustomActionSample and WV2DeploymentWiXBurnBundleSample use the reg name EBWebView for registry searching, but this entry has already disappeared in recent versions of WVRT (also disappeared in Edge Stable).

Changed them to pv, consistent with WV2DeploymentVSInstallerSample.

Also I noticed that these three registry searches were introduced in the same PR (#56). Are there any special considerations for the inconsistency here?

Related commit:

https://github.com/MicrosoftEdge/WebView2Samples/commit/8402697ac016014ca90a0168ef0059428102818e