DEV: git ignored directories should not have trailing slashes (#27130)

VS Code is configured to automatically excludes files and directories from the `.gitignore` but the trailing slash was not working as expected.

The plugins that had a trailing slash in the .gitignore weren't allow-listed properly in VS Code.

.gitignore

@@ -35,20 +35,20 @@
 
 # Plugins except for the bundled ones
 /plugins/*
-!/plugins/discourse-details/
+!/plugins/discourse-details
 !/plugins/discourse-local-dates
 !/plugins/discourse-narrative-bot
 !/plugins/discourse-presence
-!/plugins/discourse-lazy-videos/
+!/plugins/discourse-lazy-videos
-!/plugins/automation/
+!/plugins/automation
 /plugins/automation/gems
-!/plugins/chat/
+!/plugins/chat
-!/plugins/poll/
+!/plugins/poll
 !/plugins/styleguide
-!/plugins/spoiler-alert/
+!/plugins/spoiler-alert
-!/plugins/checklist/
+!/plugins/checklist
-!/plugins/footnote/
+!/plugins/footnote
-/plugins/*/auto_generated/
+/plugins/*/auto_generated
 
 /spec/fixtures/plugins/my_plugin/auto_generated
 
@@ -71,7 +71,7 @@ yarn-error.log
 
 # Linting artifacts
 .eslintcache
-/lint-progress/
+/lint-progress
 
 # Auto-generated plugin JS assets
 /app/assets/javascripts/plugins/*