Deb: Remove PLUGIN_COLUMNSTORE=YES, it will build by default anyway

If PLUGIN_COLUMNSTORE is not defined, ColumnStore will build automatically
by default on supported architectures as defined in its CMakeFile.txt.

Thus there should not be any need to inject this build flag at any point
and it can be removed to keep thing lean and clean.

debian/rules

@@ -48,12 +48,6 @@ ifeq (32,$(DEB_HOST_ARCH_BITS))
     CMAKEFLAGS += -DPLUGIN_ROCKSDB=NO
 endif
 
-# ColumnStore only attempts to build on a few platforms as dictated by CMake checks
-# Also note in debian/control the CS-only build deps marked '[amd64]'
-ifeq ($(DEB_HOST_ARCH),$(filter $(DEB_HOST_ARCH),amd64))
-    CMAKEFLAGS += -DPLUGIN_COLUMNSTORE=YES
-endif
-
 # Add extra flag to avoid WolfSSL code crashing the entire mariadbd on s390x. This
 # can be removed once upstream has made the code s390x compatible, see
 # https://jira.mariadb.org/browse/MDEV-21705 and