patch 9.0.0704: CI runs "tiny" and "small" builds, which are the same

Problem:    CI runs "tiny" and "small" builds, which are the same.
Solution:   Remove the "small" build. (Naruhiko Nishino, closes #11315)
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index c988949..d92f6df 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -33,7 +33,7 @@
     strategy:
       fail-fast: false
       matrix:
-        features: [tiny, small, normal, huge]
+        features: [tiny, normal, huge]
         compiler: [clang, gcc]
         extra: [none]
         include:
@@ -125,7 +125,7 @@
           echo "TMPDIR=${{ runner.temp }}"
 
           case "${{ matrix.features }}" in
-          tiny|small)
+          tiny)
             echo "TEST=testtiny"
             if ${{ contains(matrix.extra, 'nogui') }}; then
               echo "CONFOPT=--disable-gui"