Don't strip debugging symbols in the regular Debian images

Since #687, the regular Debian images no longer ship DWARF symbols,
which heavily limits the ability to use gdb and lldb for debugging.

Stripping debugging symbols makes perfect sense to reduce the size
of Docker images, but when this optimization was first introduced
in #483, the idea was to restrict its use to the slim and Alpine images.
That was (unintentionally?) changed in #483, and now debugging symbols
are also stripped in the regular Debian images. Undo that change.

Author: malor

3.10/bullseye/Dockerfile

@@ -170,7 +170,9 @@ RUN set -eux; \
 # https://github.com/alpinelinux/aports/commit/2026e1259422d4e0cf92391ca2d3844356c649d0
 		EXTRA_CFLAGS="-DTHREAD_STACK_SIZE=0x100000" \
 {{ ) else "" end -}}
+{{ if is_slim or is_alpine then ( -}}
 		LDFLAGS="-Wl,--strip-all" \
+{{ ) else "" end -}}
 {{ if env.version == "3.7" then ( -}}
 # setting PROFILE_TASK makes "--enable-optimizations" reasonable: https://bugs.python.org/issue36044 / https://github.com/docker-library/python/issues/160#issuecomment-509426916
 		PROFILE_TASK='-m test.regrtest --pgo \