Gitlab CI: add build check for 2 tools that are off by default.

This is to avoid issues like https://gitlab.com/AOMediaCodec/avm/-/issues/401 and https://gitlab.com/AOMediaCodec/avm/-/issues/400 in future.

.gitlab-ci.yml

diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index f7d8cab..550b39b 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -231,6 +231,12 @@
         entropy-stats)
           CMAKE_FLAGS="$CMAKE_FLAGS -DCONFIG_ENTROPY_STATS=1"
           ;;
+        ml-part-split)
+          CMAKE_FLAGS="$CMAKE_FLAGS -DCONFIG_ML_PART_SPLIT=1"
+          ;;
+        bawp-across-scales-fix)
+          CMAKE_FLAGS="$CMAKE_FLAGS -DCONFIG_BAWP_ACROSS_SCALES_FIX=1"
+          ;;
         nasm)
           CMAKE_FLAGS="$CMAKE_FLAGS -DENABLE_NASM=1"
           ;;
@@ -323,6 +329,23 @@
       - AOM_BUILD_CONFIG:
           - entropy-stats
 
+Build (ml-part-split):
+  extends: .build-common
+  variables:
+    # Allow build warnings.
+    EXTRA_CMAKE_FLAGS: -DENABLE_WERROR=0
+  parallel:
+    matrix:
+      - AOM_BUILD_CONFIG:
+          - ml-part-split
+
+Build (bawp-across-scales-fix):
+  extends: .build-common
+  parallel:
+    matrix:
+      - AOM_BUILD_CONFIG:
+          - bawp-across-scales-fix
+
 Build (x86-linux-gcc):
   extends: .build-common
   image: registry.gitlab.com/aomediacodec/aom-testing/ubuntu2204-multilib:20231215235031