Fix larger gallery image uploading (#4292)

This reconciles a couple of differences between the frontend and backend regarding gallery image uploads.

- Frontend: The frontend thought that the limit should be 500 MiB for gallery images. This is obviously not right. It has been updated to 5 MiB.
- Backend: The backend has been rejecting anything between 2 MiB and 5 MiB, but this is inconsistent with prior usage, where the limit used to be 5 MiB. It has been updated to allow anything under 5 MiB.

Fixes #4291

apps/frontend/src/pages/[type]/[id]/gallery.vue

@@ -15,7 +15,7 @@
 							class="iconified-button raised-button"
 							prompt="Replace"
 							:accept="acceptFileTypes"
-							:max-size="524288000"
+							:max-size="5242880"
 							should-always-reset
 							aria-label="Replace image"
 							@change="
@@ -197,7 +197,7 @@
 		</div>
 		<div v-if="currentMember" class="card header-buttons">
 			<FileInput
-				:max-size="524288000"
+				:max-size="5242880"
 				:accept="acceptFileTypes"
 				prompt="Upload an image"
 				aria-label="Upload an image"