tests/docker: use debian-all-test-cross for mips64el tests

While the mips64el cross compilation environment is busted in Debian
we can use the debian-all-test-cross image for building TCG tests like
we do in the CI.

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20240910173900.4154726-4-alex.bennee@linaro.org>

configure

@@ -1328,7 +1328,7 @@ probe_target_compiler() {
         container_cross_prefix=microblaze-linux-musl-
         ;;
       mips64el)
-        container_image=debian-mips64el-cross
+        container_image=debian-all-test-cross
         container_cross_prefix=mips64el-linux-gnuabi64-
         ;;
       tricore)