ci: update Eclipse R search method2

Author: AndriiFilippov

releng/update-site-tests/detect-latest-eclipse-steams.sh

@@ -12,16 +12,14 @@ XML="$(curl -fsSL "$RELEASE_XML")"
 
 ECLIPSE_R_RELEASE="$(
   printf '%s\n' "$XML" \
-    | tr ' ' '\n' \
-    | grep -E '^[0-9]{4}-[0-9]{2}/R$' \
-    | sed 's|/R||' \
+    | grep -oE '[0-9]{4}-[0-9]{2}/R([^A-Za-z0-9]|$)' \
+    | sed -E 's|/R([^A-Za-z0-9].*)?$||' \
     | sort -r \
     | head -n1
 )"
 
 ECLIPSE_M_RELEASE="$(
   printf '%s\n' "$XML" \
-    | tr ' ' '\n' \
     | grep -E '^[0-9]{4}-[0-9]{2}/M[0-9]+$' \
     | sort -r \
     | head -n1 || true