ci,ui: fix cluster-ui-release "check if published" step

The check for whether a version exists in npm is too liberal
with its pattern matching, resulting in pre-release branches
to cause other releases to fail to publish.

Now, a pre-release version will not cause a potential
failure in publish a regular version release.

Epic: None
Release note: None

Author: kyle-a-wong

.github/workflows/cluster-ui-release.yml

@@ -58,7 +58,7 @@ jobs:
       run: |
         PACKAGE_VERSION=$(cat ./package.json | jq -r ".version");
         VERSIONS=$(npm view @cockroachlabs/cluster-ui versions)
-        if [[ $VERSIONS == *"$PACKAGE_VERSION"* ]]; then
+        if [[ $VERSIONS == *\'"$PACKAGE_VERSION"\'* ]]; then
           echo "published=yes" >> $GITHUB_OUTPUT
           echo
           echo "🛑 Cluster UI package version $PACKAGE_VERSION is already published"