nixos/pixelfed: cleanup package cache at the very start

(cherry picked from commit db23065)

nixos/modules/services/web-apps/pixelfed.nix

@@ -380,6 +380,12 @@ in {
       };
 
       script = ''
+        # Before running any PHP program, cleanup the bootstrap.
+        # It's necessary if you upgrade the application otherwise you might
+        # try to import non-existent modules.
+        rm -f ${cfg.runtimeDir}/bootstrap/app.php
+        rm -rf ${cfg.runtimeDir}/bootstrap/cache/*
+
         # Concatenate non-secret .env and secret .env
         rm -f ${cfg.dataDir}/.env
         cp --no-preserve=all ${configFile} ${cfg.dataDir}/.env
@@ -406,11 +412,6 @@ in {
         # Install Horizon
         # FIXME: require write access to public/ — should be done as part of install — pixelfed-manage horizon:publish
 
-        # Before running any PHP program, cleanup the bootstrap.
-        # It's necessary if you upgrade the application otherwise you might
-        # try to import non-existent modules.
-        rm -rf ${cfg.runtimeDir}/bootstrap/*
-
         # Perform the first migration.
         [[ ! -f ${cfg.dataDir}/.initial-migration ]] && pixelfed-manage migrate --force && touch ${cfg.dataDir}/.initial-migration