Move TetheringTests to presubmit

The TetheringTests are green in postsubmit for a while.
Also add TetheringIntegrationTests to postsubmit.

Bug: 148998835
Test: atest --test-mapping frameworks/base/packages/Tethering:postsubmit
      atest --test-mapping frameworks/base/packages/Tethering:presubmit
Merged-In: I80d29d06fde5a718c31a0a5ad2e2562be5bf419f
Change-Id: I80d29d06fde5a718c31a0a5ad2e2562be5bf419f