Remove unused `tags` property from Android.bp files

The tags property is (and has always been) unused by Soong. The property has
been defined as a list of strings, and the `androidmk` converted any
LOCAL_MODULE_TAGS entries over to it, but we've never done anything with it.

In preparation for removing the definition from Soong, I'm removing it from all
Android.bp files in the tree.

Since this has never done anything, this is a no-op, but if you really did want
the Android.mk behavior, the proper way to define a module to be installed in
userdebug / eng builds is to use PRODUCT_PACKAGES_DEBUG or PRODUCT_PACKAGES_ENG
in the appropriate product makefile.

Change-Id: I4a6a26cd7e139c19f63e02d6e1e7a2617c55b72d
Exempt-From-Owner-Approval: global no-op build change
Test: remove `tags` from Soong, see errors go away.