Temporarily withdraw image/avif from MediaType.

As in cl/728267849, there is nothing wrong with it, and we will add it
in version 33.5.0. I'm removing it merely so that we can publish our
next release as a _patch_ release, rather than as a _minor_ release.

Author: cpovirk

android/guava/src/com/google/common/net/MediaType.java

@@ -252,13 +252,6 @@ private static MediaType addKnownType(MediaType mediaType) {
   public static final MediaType SVG_UTF_8 = createConstantUtf8(IMAGE_TYPE, "svg+xml");
   public static final MediaType TIFF = createConstant(IMAGE_TYPE, "tiff");
 
-  /**
-   * <a href="https://en.wikipedia.org/wiki/AVIF">AVIF image format</a>.
-   *
-   * @since NEXT
-   */
-  public static final MediaType AVIF = createConstant(IMAGE_TYPE, "avif");
-
   /**
    * <a href="https://en.wikipedia.org/wiki/WebP">WebP image format</a>.
    *

guava/src/com/google/common/net/MediaType.java

@@ -252,13 +252,6 @@ private static MediaType addKnownType(MediaType mediaType) {
   public static final MediaType SVG_UTF_8 = createConstantUtf8(IMAGE_TYPE, "svg+xml");
   public static final MediaType TIFF = createConstant(IMAGE_TYPE, "tiff");
 
-  /**
-   * <a href="https://en.wikipedia.org/wiki/AVIF">AVIF image format</a>.
-   *
-   * @since NEXT
-   */
-  public static final MediaType AVIF = createConstant(IMAGE_TYPE, "avif");
-
   /**
    * <a href="https://en.wikipedia.org/wiki/WebP">WebP image format</a>.
    *