CI tester-exec.sh: reduce use of variables

If a variable is used only once, or just decodes part of name
by adding it as part of variable name, it is not really helpful.
Reduce amount of lines by not defining such variables.

Signed-off-by: Olev Kartau <olev.kartau@intel.com>

docker/tester-exec.sh

@@ -21,7 +21,6 @@ testimg() {
   _IMG_NAME=$1
   TEST_SUITE_FILE=$2
   TEST_CASES_FILE=$3
-  _IMG_NAME_MACHINE=${_IMG_NAME}-${MACHINE}
 
   # Get test suite
   wget ${_WGET_OPTS} ${TEST_SUITE_FOLDER_URL}/${_IMG_NAME}/${TEST_SUITE_FILE}
@@ -34,21 +33,16 @@ testimg() {
   cp $HOME/.config.ini.wlan ${_WLANCONF}
   chmod 644 ${_WLANCONF}
 
-  FN_BASE=${_IMG_NAME_MACHINE}-${CI_BUILD_ID}
-  FILENAME=${FN_BASE}.wic
-  FILENAME_BMAP=${FILENAME}.bmap
-  FILENAME_XZ=${FILENAME}.xz
-  FILENAME_ZIP=${FILENAME}.zip
-
+  FILENAME=${_IMG_NAME}-${MACHINE}-${CI_BUILD_ID}.wic
   set +e
-  wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME_BMAP}
-  wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME_XZ} -O - | unxz - > ${FILENAME}
+  wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME}.bmap
+  wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME}.xz -O - | unxz - > ${FILENAME}
   if [ ! -s ${FILENAME} ]; then
-    wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME_ZIP}
-    if [ -s ${FILENAME_ZIP} ]; then
-      unzip ${FILENAME_ZIP}
+    wget ${_WGET_OPTS} ${CI_BUILD_URL}/images/${MACHINE}/${FILENAME}.zip
+    if [ -s ${FILENAME}.zip ]; then
+      unzip ${FILENAME}.zip
     else
-      echo "ERROR: No file ${FILENAME_XZ} or ${FILENAME_ZIP} found, can not continue."
+      echo "ERROR: No file ${FILENAME}.xz or ${FILENAME}.zip found, can not continue."
       exit 1
     fi
   fi