Remove loop-build harness and associated configuration files.

loop-build/config/allowlist.txt

@@ -0,0 +1,27 @@
+ls
+ls -la
+cat
+rg
+grep
+tree
+git status
+git diff
+git rev-parse
+git log
+git show
+git branch
+git branch --show-current
+git status --short
+git blame
+sed
+awk
+head
+tail
+wc
+printf
+echo
+find
+pwd
+git restore --source
+true
+false