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)
diff --git a/adb/client/commandline.cpp b/adb/client/commandline.cpp
index a5cfd7f..6e143c1 100644
--- a/adb/client/commandline.cpp
+++ b/adb/client/commandline.cpp
@@ -158,7 +158,7 @@
         "     --instant: cause the app to be installed as an ephemeral install app\n"
         "     --no-streaming: always push APK to device and invoke Package Manager as separate steps\n"
         "     --streaming: force streaming APK directly into Package Manager\n"
-        "     -f/--fastdeploy: use fast deploy (only valid with -r)\n"
+        "     --fastdeploy: use fast deploy (only valid with -r)\n"
         "     --no-fastdeploy: prevent use of fast deploy (only valid with -r)\n"
         "     --force-agent: force update of deployment agent when using fast deploy\n"
         "     --date-check-agent: update deployment agent when local version is newer and using fast deploy\n"