Remove unnecessary java_language property

1.7 is no longer supported by kotlinc, remove the unnecessary property
and let it use the default.

Bug: 216136346
Test: m checkbuild
Change-Id: If479dafb0fd813b301c985c74f7076a6796aa004
(cherry picked from commit 10e9c1355fe519dbc9a228e7711074a38073c620)
Merged-In: If479dafb0fd813b301c985c74f7076a6796aa004
diff --git a/Android.bp b/Android.bp
index 6924ca2..7830fbb 100644
--- a/Android.bp
+++ b/Android.bp
@@ -28,5 +28,4 @@
         "-Xmulti-platform",
     ],
     sdk_version: "current",
-    java_version: "1.7",
 }