Remove unused flags

Release-Notes: skip
Change-Id: I397ccac088e4cfd579cc3218228fd55df73c6c5d

polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts

diff --git a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
index de92b16..23dce97 100644
--- a/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
+++ b/polygerrit-ui/app/elements/diff/gr-diff-host/gr-diff-host.ts
@@ -347,9 +347,7 @@
     );
     this.renderPrefs = {
       ...this.renderPrefs,
-      use_lit_components: this.flags.isEnabled(
-        KnownExperimentId.DIFF_RENDERING_LIT
-      ),
+      use_lit_components: true,
     };
     this.addEventListener(
       // These are named inconsistently for a reason:

polygerrit-ui/app/services/flags/flags.ts

diff --git a/polygerrit-ui/app/services/flags/flags.ts b/polygerrit-ui/app/services/flags/flags.ts
index 2a5dff2..ad15a62 100644
--- a/polygerrit-ui/app/services/flags/flags.ts
+++ b/polygerrit-ui/app/services/flags/flags.ts
@@ -17,7 +17,6 @@
   NEW_IMAGE_DIFF_UI = 'UiFeature__new_image_diff_ui',
   CHECKS_DEVELOPER = 'UiFeature__checks_developer',
   PUSH_NOTIFICATIONS_DEVELOPER = 'UiFeature__push_notifications_developer',
-  DIFF_RENDERING_LIT = 'UiFeature__diff_rendering_lit',
   PUSH_NOTIFICATIONS = 'UiFeature__push_notifications',
   SUGGEST_EDIT = 'UiFeature__suggest_edit',
   MENTION_USERS = 'UiFeature__mention_users',