vendor.mime.types: Revert accidental modification.

I had added some lines during verification of the base CL [1], but had
accidentally committed, uploaded and merged them. This CL reverts the
accidental addition.

[1] r.android.com/1136528 commit 8e1c1f4d

Bug: 142267887
Test: Treehugger
Change-Id: If9ef2a956c8862b7022137111e6c512455780fc6

mime/java-res/vendor.mime.types

@@ -39,6 +39,3 @@
 #
 # Add your custom mappings below this line (with no "#" at the start of the line):
 
-test/mimeA extA extB extX
-?test/mimeC ?extX ?extY ?extZ
-test/mimeB extC ?extD extF