Ensure Go binary exists before version check (#7059)

A missing Go binary during checking go version can cause script failure. The condition check
failed to handle this case because the directory still existed.

This patch improves the directory check by directly verifying the existence of `bin/go`
to prevent script failure when retrieving go version.

Signed-off-by: Shuyang Xin <[email protected]>

Author: XinShuYang

ci/jenkins/utils.sh

@@ -44,7 +44,7 @@ function check_and_upgrade_golang() {
     while read -r i; do
         version=$(echo ${i} | jq .version | tr -d '"')
         if [[ "${version}" =~ "${antrea_golang_version}" ]]; then
-            if [ -d "${GOLANG_RELEASE_DIR}/${antrea_golang_version}" ]; then
+            if [ -f "${GOLANG_RELEASE_DIR}/${antrea_golang_version}/bin/go" ]; then
                 current_version=$(${GOLANG_RELEASE_DIR}/${antrea_golang_version}/bin/go version | awk '{print $3}')
                 if [[ "${version}" == "${current_version}" ]]; then
                     echo "====== Golang ${version} is installed on the testbed, no need to download ======"