Add 'xap' branch to CI workflow and options (#25708)

.github/workflows/ci_build_major_branch.yml

@@ -6,13 +6,13 @@ permissions:
 
 on:
   push:
-    branches: [master, develop]
+    branches: [master, develop, xap]
   workflow_dispatch:
     inputs:
       branch:
         type: choice
         description: "Branch to build"
-        options: [master, develop]
+        options: [master, develop, xap]
 
 env:
   # https://docs.github.com/en/actions/learn-github-actions/usage-limits-billing-and-administration#usage-limits
@@ -52,7 +52,7 @@ jobs:
         run: |
           target_count=$( {
             qmk find -km default 2>/dev/null
-            # qmk find -km xap 2>/dev/null
+            qmk find -km xap 2>/dev/null
           } | sort | uniq | wc -l)
           slice_length=$((target_count / ($CONCURRENT_JOBS - 1))) # Err on the side of caution
           echo "slice_length=$slice_length" >> $GITHUB_OUTPUT
@@ -63,8 +63,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        keymap: [default]
-        # keymap: [default, xap]
+        keymap: [default, xap]
     uses: ./.github/workflows/ci_build_major_branch_keymap.yml
     with:
       branch: ${{ inputs.branch || github.ref_name }}