[KYUUBI #7571] [INFRA] Redirect build/mvn fallback message to stderr to avoid corrupting captures

### Why are the changes needed?

For example, the Spark version was wrongly captured as `Falling back to archive.apache.org to download Maven`

https://github.com/apache/kyuubi/actions/runs/29387027103/job/87262361668?pr=7570

### How was this patch tested?

Merge then monitor CI.

### Was this patch authored or co-authored using generative AI tooling?

No.

Closes #7571 from pan3793/mvn-echo.

Closes #7571

83b48e1 [Cheng Pan] [INFRA] Redirect build/mvn fallback message to stderr to avoid corrupting captures

Authored-by: Cheng Pan <chengpan@apache.org>
Signed-off-by: Cheng Pan <chengpan@apache.org>
(cherry picked from commit 6a68db3)
Signed-off-by: Cheng Pan <chengpan@apache.org>

Author: pan3793

build/mvn

@@ -54,8 +54,8 @@ install_app() {
     wget ${wget_opts} -O "${local_tarball}" "${remote_tarball}"
   # if both were unsuccessful, exit
   [ ! -f "${local_tarball}" ] && \
-    echo -n "ERROR: Cannot download $2 with cURL or wget; " && \
-    echo "please install manually and try again." && \
+    echo -n "ERROR: Cannot download $2 with cURL or wget; " 1>&2 && \
+    echo "please install manually and try again." 1>&2 && \
     exit 2
   cd "${_DIR}" && tar -xzf "$2"
   rm -rf "$local_tarball"
@@ -85,7 +85,7 @@ install_mvn() {
     if [ $(command -v curl) ]; then
       if ! curl -L --output /dev/null --silent --head --fail "${APACHE_MIRROR}/${FILE_PATH}/${MVN_TARBALL}${MIRROR_URL_QUERY}" ; then
         # Fall back to archive.apache.org for older Maven
-        echo "Falling back to archive.apache.org to download Maven"
+        echo "Falling back to archive.apache.org to download Maven" 1>&2
         APACHE_MIRROR="https://archive.apache.org/dist"
         MIRROR_URL_QUERY=""
       fi