JS: fix npmPublish skip detection that always reported "already published"

PR #7552 added an `onlyIf` block that ran `npm view @openrewrite/rewrite@<version>
version` and skipped publishing if the captured output contained the version
string. With `redirectErrorStream(true)`, npm's 404 error message also contains
the requested version (e.g. "The requested resource '@openrewrite/rewrite@<version>'
could not be found"), so the contains-check matched on every miss and silently
skipped npm publish for any newly-stamped snapshot.

The npm prerelease tag has been frozen at 8.82.0-20260502-150813 since then,
while Maven snapshots continue to advance with the latest commit timestamp.
Downstream consumers that try to spawn the JS RPC subprocess via
`npx --package=@openrewrite/rewrite@<jar-version> rewrite-rpc` then fail with
ETARGET because the version baked into the JAR's resource is not on npm,
breaking CI in repositories like rewrite-static-analysis.

Switch the check to use `npm view`'s exit code (and verify the version appears
on its own line in stdout) so we only skip when the version is genuinely
already published.

Author: timtebeek

rewrite-javascript/build.gradle.kts

@@ -263,9 +263,8 @@ val npmPublish = tasks.register<NpmTask>("npmPublish") {
             .directory(file("rewrite"))
             .redirectErrorStream(true)
             .start()
-        process.waitFor()
         val output = process.inputStream.bufferedReader().readText().trim()
-        val alreadyPublished = output.contains(versionToCheck)
+        val alreadyPublished = process.waitFor() == 0 && output.lines().any { it.trim() == versionToCheck }
         if (alreadyPublished) {
             logger.lifecycle("Skipping npmPublish: @openrewrite/rewrite@$versionToCheck already published")
         }