Revert "`clj -M:run` should not think it's running in `:dev` mode (#30004)" (#30043)

This reverts commit 8a11e382.

The namespace `metabase.server.middleware.security` controls our content
security policy header. In dev we allow connections to 8080 for webpack
assets. Not dev we deny these.

`clj -M:run` is dev since it is running the project from source, not a
jar. This `mb.run.mode` was removed when we were fighting require issues
for `metabase.query-processor-test.test-mlv2`. That's solved so we can
restore the dev property to `:run`.

deps.edn

@@ -262,7 +262,8 @@
   ;; clojure -M:run:ee (include EE code)
   :run
   {:main-opts ["-m" "metabase.bootstrap"]
-   :jvm-opts  ["-Djava.awt.headless=true"                   ; prevent Java icon from randomly popping up in macOS dock
+   :jvm-opts  ["-Dmb.run.mode=dev"
+               "-Djava.awt.headless=true"                   ; prevent Java icon from randomly popping up in macOS dock
                "-Dmb.jetty.port=3000"]}
 
   ;; alias for CI-specific options.