chore(typo): fix spacing typo in gradle plugin message (#33619)

Summary:
There is a simple typo - a missing space in to string concatenation in a deprecation message, the message pops up in a newly initialized RN68 project so seems worth fixing

## Changelog

<!-- Help reviewers and the release process by writing your own changelog entry. For an example, see:
https://github.com/facebook/react-native/wiki/Changelog
-->

[Android] [Fixed] - Fix typo in gradle plugin deprecation message

Pull Request resolved: https://github.com/facebook/react-native/pull/33619

Test Plan:
Fixed via visual inspection (adding a single space character is luckily easy like that, yes that's perhaps over-confident but if you see the diff you will probably agree?)

cortinico

Reviewed By: cortinico

Differential Revision: D35577039

Pulled By: GijsWeterings

fbshipit-source-id: 84dc28ca0d0dcce89e1ca0c39ab0357b59396073

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/ReactExtension.kt

@@ -248,7 +248,7 @@ abstract class ReactExtension @Inject constructor(project: Project) {
    * Please also note that those are the default value and you most likely don't need those at all.
    */
   @Deprecated(
-      "reactRoot was confusing and has been replace with root" +
+      "reactRoot was confusing and has been replace with root " +
           "to point to your root project and reactNativeDir to point to " +
           "the folder of the react-native NPM package",
       replaceWith = ReplaceWith("reactNativeRoot"))