docs: Fixing bad unicode sequence in Javadocs.

The source file /external/icu/icu4j/main/classes/…/UnicodeSet.java
has a comment with the character sequence '\u0000', which is being
output verbatim to a Javadoc comment the generated file
java/android/icu/text/UnicodeSet.java . (See bug b/32309442)

That character sequence is being output as a null byte in the
generated HTML file: https://screenshot.googleplex.com/ixQ4G2QTZkY.png
https://developer.android.com/reference/android/icu/text/UnicodeSet.html#applyPropertyAlias(java.lang.String,%20java.lang.String)

Besides generating bad documentation (the sequence shows up as "\u"
instead of "\u0000"), this also means we won't be able to check the
generated docs in to Piper as text files.

Per instructions from JS, I've modified the external file, run the
script to generate the java/android/icu file from it, and included
both files in this CL. I've also generated the Javadoc from the
modified file and staged it to:

https//go/dods-stage/reference/android/icu/text/UnicodeSet.html#applyPropertyAlias(java.lang.String,%20java.lang.String)

NOTE: Currently, a double-backslash sequence is incorrectly output to
the Javadoc as a double-backslash instead of being treated as an
escape character. I filed a separate bug about that, b/32335850

bug: 32309442
Change-Id: If25fe0767769ecf15d5f8b73a18eb9e0f87b3752
(cherry picked from commit 06ec6d9c5ca6a2e72ac506c8729e0a31db19e211)
diff --git a/android_icu4j/src/main/java/android/icu/text/UnicodeSet.java b/android_icu4j/src/main/java/android/icu/text/UnicodeSet.java
index 9d934ae..c4d8009 100644
--- a/android_icu4j/src/main/java/android/icu/text/UnicodeSet.java
+++ b/android_icu4j/src/main/java/android/icu/text/UnicodeSet.java
@@ -3318,8 +3318,8 @@
      * property alias, or a special ID.  Special IDs are matched
      * loosely and correspond to the following sets:
      *
-     * "ANY" = [\u0000-\U0010FFFF],
-     * "ASCII" = [\u0000-\u007F].
+     * "ANY" = [\\u0000-\\u0010FFFF],
+     * "ASCII" = [\\u0000-\\u007F].
      *
      * @param valueAlias a value alias, either short or long.  The
      * name is matched loosely.  See PropertyValueAliases.txt for
diff --git a/icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSet.java b/icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSet.java
index 957bb82..bcdaf24 100644
--- a/icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSet.java
+++ b/icu4j/main/classes/core/src/com/ibm/icu/text/UnicodeSet.java
@@ -3393,8 +3393,8 @@
      * property alias, or a special ID.  Special IDs are matched
      * loosely and correspond to the following sets:
      *
-     * "ANY" = [\u0000-\U0010FFFF],
-     * "ASCII" = [\u0000-\u007F].
+     * "ANY" = [\\u0000-\\u0010FFFF],
+     * "ASCII" = [\\u0000-\\u007F].
      *
      * @param valueAlias a value alias, either short or long.  The
      * name is matched loosely.  See PropertyValueAliases.txt for