github: Remove most builds with leak detective

As mentioned in the previous commit, ASAN does a fine job detecting leaks
during the tests.  We just add a single LD-enabled build of the "default"
test here to test the basic functionality.
And we continue to use leak detective in our testing environment to keep
the memory requirements low.

We don't need a separate cache for the "apidoc" test and while the
"dist" test is similar as well, it builds in a different directory,
which means that config.h causes a cache miss for everything but the
configure checks.

scripts/test.sh

@@ -211,7 +211,7 @@ DEPS="libgmp-dev"
 CFLAGS="-g -O2"
 
 case "$TEST" in
-default)
+default|ld)
 	# should be the default, but lets make sure
 	CONFIG="--with-printf-hooks=glibc"
 	if system_uses_openssl3; then