[github-acction] build jobs failure due to deprecated macOS-12 enviro…

…nment

The macOS-12 environment is deprecated, consider switching to macOS-13, macOS-14 (macos-latest) or macOS-15.

For more details, see actions/runner-images#10721

In addition, removing -s option because the -s option is not supported
by the realpath command in macOS 13 (Ventura) and later versions, so execute realpath differently depending on Linux and MacOS.

tests/integration/common.sh

@@ -29,14 +29,7 @@
 
 ## This file defines constants and common functions for test cases.
 
-if [ "$(uname)" = "Linux" ]; then
-    echo "OS is Linux"
-    readonly CUR_DIR="$(dirname "$(realpath -s "$0")")"
-elif [ "$(uname)" = "Darwin" ]; then
-    echo "OS is Darwin"
-    readonly CUR_DIR="$(dirname "$(realpath "$0")")"
-fi
-
+readonly CUR_DIR="$(dirname "$(realpath -s "$0")")"
 readonly TEST_ROOT_DIR=${CUR_DIR}
 
 readonly RUNTIME_DIR=/tmp/test-ot-commissioner