Support Matrix 1.1 (drop legacy r0 versions) (#9819)

Co-authored-by: Michael Telatynski <7t3chguy@gmail.com>

test/components/views/messages/__snapshots__/MImageBody-test.tsx.snap

@@ -6,7 +6,7 @@ exports[`<MImageBody/> should generate a thumbnail if one isn't included for ani
     class="mx_MImageBody"
   >
     <a
-      href="https://server/_matrix/media/r0/download/server/image"
+      href="https://server/_matrix/media/v3/download/server/image"
     >
       <div
         class="mx_MImageBody_thumbnail_container"

test/components/views/messages/__snapshots__/MVideoBody-test.tsx.snap

@@ -37,7 +37,7 @@ exports[`MVideoBody should show poster for encrypted media before downloading it
         class="mx_MVideoBody"
         controls=""
         controlslist="nodownload"
-        poster="https://server/_matrix/media/r0/download/server/encrypted-poster"
+        poster="https://server/_matrix/media/v3/download/server/encrypted-poster"
         preload="none"
         title="alt for a test video"
       />