ci(react-sdk): remove release version pinning (#1345)

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<!-- CURSOR_SUMMARY -->
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> [!NOTE]
> **Low Risk**
> Low risk CI/release automation change that only affects how
`release-please` determines the next version for `packages/sdk/react`.
Main risk is unintended version bumps if prior manual pinning was relied
on.
> 
> **Overview**
> Removes the `release-as: "4.0.0"` override for `packages/sdk/react` in
`release-please-config.json`, so `release-please` will no longer force
the React SDK to release as 4.0.0 and will instead follow normal version
calculation.
> 
> No other package release configuration is changed.
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
84aa98e. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: joker23

release-please-config.json

@@ -281,7 +281,6 @@
       "bump-minor-pre-major": true
     },
     "packages/sdk/react": {
-      "release-as": "4.0.0",
       "extra-files": [
         "src/client/LDReactClient.tsx",
         {