Remove additional --update for apk in Dockerfile (oxsecurity#2619)

There is no need to use `--update` with `--no-cache` when using `apk` on
Alpine Linux, as using `--no-cache` will fetch the index every time and
leave no local cache, so the index will always be the latest without
temporary files remain in the image.

.automation/build.py

@@ -448,7 +448,7 @@ def build_dockerfile(
     apk_install_command = ""
     if len(apk_packages) > 0:
         apk_install_command = (
-            "RUN apk add --update --no-cache \\\n                "
+            "RUN apk add --no-cache \\\n                "
             + " \\\n                ".join(list(dict.fromkeys(apk_packages)))
             + " \\\n    && git config --global core.autocrlf true"
         )

Dockerfile

@@ -78,7 +78,7 @@ WORKDIR /
 ## @generated by .automation/build.py using descriptor files, please do not update manually ##
 #############################################################################################
 #APK__START
-RUN apk add --update --no-cache \
+RUN apk add --no-cache \
                 bash \
                 ca-certificates \
                 curl \