PackageManagerShellCommand: implicitly add --wait for staged installs

Add --no-wait flag to opt-out from the waiting logic. Also changed the
prompt to remind developer to reboot a device to apply an install.

Test: adb install system/apex/shim/com.android.apex.cts.shim.v2.apex
Test: adb shell pm install-abandon
Test: adb install --no-wait system/apex/shim/com.android.apex.cts.shim.v2.apex
Bug: 147694315
Change-Id: Ic79905422935d85308d6d57a44005e71a706f2d3