Remove uglifier as JS preprocessor

Gemfile.lock

@@ -140,7 +140,7 @@ GEM
     database_cleaner-core (2.0.1)
     debug_inspector (1.1.0)
     diff-lcs (1.4.4)
-    docile (1.3.5)
+    docile (1.4.0)
     docker-api (2.1.0)
       excon (>= 0.47.0)
       multi_json
@@ -149,7 +149,6 @@ GEM
     erubi (1.10.0)
     eventmachine (1.2.7)
     excon (0.81.0)
-    execjs (2.8.0)
     factory_bot (6.2.0)
       activesupport (>= 5.0.0)
     factory_bot_rails (6.2.0)
@@ -475,8 +474,6 @@ GEM
     turbolinks-source (5.2.0)
     tzinfo (2.0.4)
       concurrent-ruby (~> 1.0)
-    uglifier (4.2.0)
-      execjs (>= 0.3.0, < 3)
     unf (0.1.4)
       unf_ext
     unf_ext (0.0.7.7)
@@ -576,7 +573,6 @@ DEPENDENCIES
   telegraf
   tubesock!
   turbolinks
-  uglifier
   web-console
   webmock
   webpacker