Make AndroidManifest.xml entry reference config

Make the AndroidManifest.xml service entry associated with the default
secondary LocationTimeZoneProvider reference the config value that
enables the secondary provider elsewhere. This means we can disable the
provider's service mapping with a single config value, which is good
while the AndroidManifest.xml has to contain this info.

Test: Tried with it true / false
Bug: 152746105
Change-Id: I1e1b986bbe47dd893de7ebbde5bed29ee6c034d0