ci: common: Remove 7z packaging

Removes the 7z from being package during CI, as only .tar.xz preserves
information needed on Linux, and otherwise is just extremely redundant
to package in addition to the .tar.xz.  This affects Linux releases and
PR-verify artifacts only. MSVC releases do not use this script to my
knowledge.

.ci/scripts/common/post-upload.sh

@@ -9,11 +9,5 @@ cp "${REV_NAME}-source.tar.xz" "$DIR_NAME"
 
 tar $COMPRESSION_FLAGS "$ARCHIVE_NAME" "$DIR_NAME"
 
-mv "$DIR_NAME" $RELEASE_NAME
-mv "${REV_NAME}-source.tar.xz" $RELEASE_NAME
-
-7z a "$REV_NAME.7z" $RELEASE_NAME
-
 # move the compiled archive into the artifacts directory to be uploaded by travis releases
 mv "$ARCHIVE_NAME" "${ARTIFACTS_DIR}/"
-mv "$REV_NAME.7z" "${ARTIFACTS_DIR}/"