ci: Remove git submodule related commands and parameters

We don't have any now, so no reason to bother
diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index da11515..f0cf7dc 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -436,7 +436,6 @@
     - macos
   needs: []
   variables:
-    GIT_SUBMODULE_STRATEGY: normal
     # libpcre2 gets built as a subproject, but the default Clang options on
     # macOS limit string lengths to 4095B — pcre2_error.c has a string of length
     # 4380B
diff --git a/.gitlab-ci/cache-subprojects.sh b/.gitlab-ci/cache-subprojects.sh
index 0e69266..fb0b1df 100755
--- a/.gitlab-ci/cache-subprojects.sh
+++ b/.gitlab-ci/cache-subprojects.sh
@@ -3,7 +3,6 @@
 set -e
 
 git clone --depth 1 --no-tags https://gitlab.gnome.org/GNOME/glib.git
-git -C glib submodule update --init
 meson subprojects download --sourcedir glib
 rm glib/subprojects/*.wrap
 mv glib/subprojects/ .