Small clean ups for issues raised in reviews of fastdeploy

Removed support for -f shortcut flag as this conflicts with some package manager flags
Renamed use_localagent global to match conventions
Fixed case where tmp files were created unnecessarily
Removed dead code (delete_host_file)
Cleaned up multiple layers of error handling by using fatal() as soon as error conditions occur

Fix: 113631900

Test: mm
Test: adb install -r --fastdeploy --nostreaming --force-agent --local-agent ~/example_apks/example.apk
Test: adb install -r --fastdeploy --no-streaming --force-agent --local-agent ~/example_apks/example.apk
Test: observe that fast deploy works as usual

Test: adb install -r -f --nostreaming --force-agent --local-agent ~/example_apks/example.apk
Test: adb install -r -f --no-streaming --force-agent --local-agent ~/example_apks/example.apk
Test: observe that fast deploy is no longer invoked by -f
Change-Id: Ic719df1003ac319e48b32f7f377f6f91d17f6a6f
(cherry picked from commit 0584689beaff604ceeccaf706dc368213d07b977)