Fix cloudbuild step. (#7131)

Co-authored-by: Shreya Keshive <skeshive@gmail.com>

.gcp/release-docker.yml

@@ -26,15 +26,11 @@ steps:
       - |-
         SHELL_TAG_NAME="$TAG_NAME"
         FINAL_TAG="$SHORT_SHA" # Default to SHA
-        if [[ "$$SHELL_TAG_NAME" == *"-nightly"* ]]; then
-          echo "Nightly release detected."
-          FINAL_TAG="$${SHELL_TAG_NAME#v}"
-        # Also escape the variable in the regex match
-        elif [[ "$$SHELL_TAG_NAME" =~ ^v[0-9]+\.[0-9]+\.[0-9]+$ ]]; then
-          echo "Official release detected."
+        if [[ "$$SHELL_TAG_NAME" =~ ^v[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z0-9.-]+)?$ ]]; then
+          echo "Release detected."
           FINAL_TAG="$${SHELL_TAG_NAME#v}"
         else
-          echo "Development/RC release detected. Using commit SHA as tag."
+          echo "Development release detected. Using commit SHA as tag."
         fi
         echo "Determined image tag: $$FINAL_TAG"
         echo "$$FINAL_TAG" > /workspace/image_tag.txt